Well, BP's have very poor eyesight, so unless he was really close odds are he can't really see her. More likely he's trying to decide if her habitat is bigger or better than his.

Sometimes one of mine will show interest in another. Usually on feeding day when the tubs are right next to each other and one has a rat while the other does not. The I get a lot of, "If he doesn't want that, I'll take it!" behavior.

Gale