You were definitely next. I've had this happen at my job; which is a clothing store. i'll be helping a customer find something, and then they're ready to pay. I will bring them up to the register, and sometimes there's someone else waiting to be rung up. What I try and do in that instance is find another CW to ring up the other person, if not, I simply tell them I will be right with them. Which is what we are supposed to do. 99.9% of the time, the waiting customer is fine with it. And as we don't have assigned cashiers, etc. its usually easy enough to find someone to help them quickly.