It used to be that immigration checked me and customs checked my bag. Now it happens more and more that immigration takes my luggage apart, and customs asks the immigration questions all over again. I take it this is following the same script as the triple shoe check on the way out, but it does tack a serious amount to processing time. Trick, it only seems to happen at certain airports: at BOS and JFK they do, at EWR and IAD they don't.