Absolutely nothing, there isn't anything you need to do because there isn't anything that you can do.

Keep a close eye on him, and if in the next weeks he starts to look bloated towards the tail you will know you have an issue. (we'll deal with it if it happens)

Chances are if it was a small amount that he won't have any issues at all. This happens to them in the wild all the time. Unless it was a mouthful I wouldn't be worried at all.