Do I tip the movers when they drop off today?

Sorry to post without searching the archives, but I just thought of this. 

I shipped my things from Chicago to NW England and the movers are coming in about 30 minutes to drop them off.   They aren't going to unpack anything for me.   I have about 30 boxes and a nightstand, and they're just going to put half upstairs and half downstairs for me.   It cost me about 5k USD already to ship the stuff and insure it and they've rescheduled my delivery 3 times.

Question is:   Am I supposed to tip them?


(I tipped the guys who PACKED it for me $20 each, but that was in the states in sub-zero temperatures and much more labor intensive.)

Thank you guys! 

I'm sure you'll get answers on both sides to this question. Ultimately, I think it's a nice thing to do if they do a good job - but it's not required. When I moved last summer, I packed up on one end and my bf was there when they unpacked on the other end. I told him to tip them, but he decided not to bother. Typical.

Not sure how much, but I know we tipped ours two years ago. 

I didn't tip ours and felt guilty until I realized that one of them took our DS and PSP. 

I think we gave the guys ten quid each last time.

My delivery guy was given £10 and seemed like he did not expect it but was very sweet and thanked us. It was just a straightforward "leave it all in the hallway" kind of delivery we had him do, took about twenty minutes, and we helped with the carrying too (!), no unpacking for us, we didn't need that. He was really nice so we handed him a graciously received tenner.

I bought mine a curry!