Bank Questions about Nationality

Hi,
I called my bank the other day to ask about exchange rate charges for a trip to the US I will be making. They provided the info and then about 15 mintues later I got a call back from the bank (first time in over 15 years) stating that they needed to update information on their account about me 'for tax purposes'.
They asked that nationality I was.  I stated that I am a dual citizen (I didn't specify that I am a US one and they didn't push it further). They asked if I am a UK resident and I said yes I am a UK resident with a European Passport--I did tell them details of that passport/nationality.  This was all the info they asked and they closed the call.
As a US (dual) citizen I yearly file and report on UK income including my FBAR and FATCA etc.  In my US tax documents I clearly state the name of the UK bank. Do you think I need to call the bank back and confirm I am a US citizen or is that opening a pandoras box?
Thanks,
Fred