My lo does the same thing off and on. Most of the time if he does it I take it as a sign that he is done. If he has not eaten a lot I will try to calm him down, usually I bribe him with stars, and then I will try feeding him again. Most of the time that does the trick. Sometimes not, at that point I usually give up and offer his bottle a tad bit earlier. I am not sure what I am doing is the best, but it seems to be working for us at the moment.
HTH,
Kimberly