Yes. It happens to me all the time. I was first diagnosed in 98 and by 2000 it felt totally gone but came back in 05, went away and came back in 08 and never totally left again. In 08 my subtype even changed from constipation to alternating. I've even heard of someone having 12 years without any problems at all then it changed to bother them everyday.
As for why it does it, who knows. Every time mine reappeared there wasn't anything special or different going on. It was a day just like any other. There's no constant or norm for this and just when you get used to dealing with it, it throws you a curve ball.