[Ixnert]

Hand 1: With a flop like 642 and that postflop bet from the button, there are lots of hands you could be behind to that would have called but wouldn't have raised preflop (anything that hit trips, obviously, plus any 77+ PP and A6s). The preflop pot isn't enough to make it worth the risk that button really does have a hand when he raises postflop.

Hand 2: You've got to expect that worst case, button has two overcards to your low pair and you're going for a coinflip. I don't think this is necessarily terrible, but you're not going to knock button off of his hand with your push. Maybe a good time for a stop and go?