
Regurgitation in canines is normal, it is the way they feed their young. As long as it is not too often then I would not worry I find that a large piece of food such as a lump of apple or potato may cause the regurgitation of food the dog will then often enjoy it again.
One thing I have noticed it often happens when you have given a tablet which not only means that the dog it was intended for does not get it but you are rushing about trying to stop one of the others from having it.