I do not have experience with colonies myself, but a friend of mine invited me over to look at his. If the mice and ASFs (rats are illegal here for us) felt stressed about food or water at ANY point, they would start to chew their way out. This could be just not enough places to find food, or not enough access to water. One day his ASFs water bottle ran out, and they chewed holes in the tub and got out. However, all the other colonies that had food and water plentifully remained happily in their tubs.

So is it possible there is food or water stress going on with your colonies that would cause them to feel the need to 'escape'?