That can mean a few things:
1. Your snake doesn't feel secure in its hides and is looking for another place to hide.
2. Your snake could have mites
3. Your snake might be feeling dehydrated/getting ready for a shed
4. It could be a sign that your cage temperatures are off.
5. Nothing, it could just be a random occurrence.
Generally speaking most BP's will go into their hides to digest their meal, and not come out for a few days. This isn't a hard rule, but it is common.