I am definitely not an expert, but I wouldn't think they would be likely to regurge three days after eating. Did it still look like what he ate, or different, like it had been processed (digested)? Maybe he has some form of diarhea? If it has been happening for the last two feed cycles, I would think an appoitment with your vet would be called for. Save the dark brown stuff in a small ziploc, with as much air out of it as you can manage, and take it with you to give the vet so they can see if he has any internal parasites. It wouldn't hurt to PM a couple of the really experienced guys; Adam Wysocki, RobertCoombs; to see what they say.