Anytime a group of snakes starts regurgitating meals all around a similar time period, one of the first of several possibilities is a cryptosporidia outbreak. There are a few other things that could cause this, but crypto would be a common reason under this scenerio. Another possibility would be the feeders, but that seems pretty unlikely in this case. Temps too high or low could be a cause, but they would need to be way out of the range to cause what you have seen. A virus is also another possibility. Under your travel and caging conditions as you described, I guess you will just need to keep an eye on it and see how it goes. Please keep us posted.

Kelly