Oh, yes. It got to me. I couldn't believe that a cashier felt she could be rude to me because she had to wait for me to finish up something at guest services to get her her change. It really opened my eyes to some people's real personalities.
I'd have told them if it was that big of a rush they could/should have switched registers.
I'm not sure they'd have liked that response, but it's true. Ran out of singles, register next to you is open and the GS(A/TL) is busy or not available for some reason? Move.
I don't expect most cashiers to do what I've done before, (grab a $20 bill from my register, walk over to another register take out 20 singles and put the $20 in it in its place and take the singles to the register I was on) but simply moving to another lane is not difficult.
Nor is switching the denominations between registers, but that I can see making some people freaked out for AP-related reasons, but my logic is if my hands are clearly visible to the cameras and both registers have the right amount of cash at the end of the night no harm done.