Kito does it still
He has such a determined look on his face too, when he does it, it always cracks me up.

Riley has just started to, and he looks clueless when he does it--he makes me laugh too!!

Abbey used to do it to me when she first came to live with us--that did not make me laugh (well, maybe a little). I was then told that it was a form of dominance, and not her true feelings, but she has since stopped.

I think it's fairly normal.