passport expiring. already have ILR. wanting to travel.

My US passport expires in approximately 5 months. I was granted ILR last year.
I was hoping to visit the US for 2 weeks next month. Can someone please tell me if I am going to have a problem re-entering the UK with less than 6 months on my US passport, or does it not matter because I have ILR?
How do I find out the answer for certain? I don't want to run into any surprises!
Thank you!!!!

You shouldn't have trouble, no. 

Do you know where I can find the official rule on this? I tried searching, but could not find it. Thank you.

I don't have a link to the official rule but think of this:

The reason why you are supposed to have six months remaining on a passport for entry, is that most visitors are given a six month visa stamp, making the visa valid during their entire potential stay and to know they can return home without any problems.

After your passport expires, you will continue to carry your current passport (the one that's about to expire) to show the IO the ILR sticker, meaning that they will admit you based on that sticker, not based on your new passport (although you need a new valid passport)

Hopefully that eases your concerns a bit.

Thank you for your reply. Do you know where I should look or whom I should call just so I can find out and be absolutely sure? Thank you again.

I can't even find a section on the Home Office site that covers this topic. Nor do I know who to contact or how to contact them to find out for sure. This is so stressful. I wanted to buy a plane ticket this weekend. I just wanted to go to the US for 2 weeks in July. My passport expires at the end of December. It doesnt seem like there is time to renew it before I wanted to go. Would an airline know?? Sorry for pushing this topic, but I'm desperate.

I don't think there's going to be any specific language you will find to cover your situation.  Here is something that may make you feel better.  This is what it says for visa applicants from the US about documents you need for your application:
 

a valid passport or travel document - you are not legally required to have 6 months' validity on your passport at the time when you apply for your visa, but your passport must be valid when you apply and when you arrive in the UK;

http://www.ukba.homeoffice.gov.uk/countries/usa/applying/processing-hub/?langname=UK%20English

I can't even find a section on the Home Office site that covers this topic. Nor do I know who to contact or how to contact them to find out for sure. This is so stressful. I wanted to buy a plane ticket this weekend. I just wanted to go to the US for 2 weeks in July. My passport expires at the end of December. It doesnt seem like there is time to renew it before I wanted to go. Would an airline know?? Sorry for pushing this topic, but I'm desperate.

My passport expires in mid-January. I'm going to Florida for two weeks in July. I am doing a same-day passport renewal whilst I'm home at a Passport Agency. You need to have proof of an international flight within two weeks of your appointment. The process seems relatively simple. More info on the State Department website: http://travel.state.gov/passport/npic/agencies/agencies_913.html

After my passport was "held hostage" by the Home Office for eight months when I applied for FLR(M), the thought of being without my passport for more than a couple of hours sends me into a panic attack. Plus my father is not in good health so there is no telling when I may need to fly home unexpectedly.  So my mother suggested doing it this way whilst I'm in the States.

Many thanks to you all for the info. I appreciate it.
Geeta, thank you for your help. That section did put my fears to rest.
KFdancer, yes makes sense. Thank you.
OldHarpy, that's a great idea! Thanks for the link. I do NOT want to be without my passport for similar reasons.

OK, going to book flights!

We recently renewed our USA passports... Have had to carry the old cancelled passport with the ILR visa sticker to re-enter the UK , because obviously our new US passports don't have it .Have entered the UK twice now doing that with no problems.