Yes it's very common for them them to go a couple of weeks or wait to a shed. And if you handle them on a regular basis you should be able to notice I beleive what some refer to as "sausage butt". Their lower section before their vent has a swollen appearance. It's good to spot so you don't get a surprise while handling them.
My girl gets what I call "poop butt" often. I've never had a snake go on me but my roommate did! He just got his albino that day, and was literally talking about how it's never happened before and won't happen and boom.... right on him. Peed and pooped all over him.