As long as you're c-betting half pot when you flop AJ as well, I'm happy with the bet sizing, especially given that BB only has a half stack to begin with. I've made a point in making smaller c-bets since I'm generally bluffing when I make them and that accomplishes two things:
1. I give myself better odds
on my bluffs, and
2. When I have something decent, calling a check/raise isn't quite as expensive.
This has to be weighed against the risk that we fail to get full stacks in when flop a monster, and with the risk of giving draws good pot/implied odds to call us. Knowing a little about the opponent goes a long way here; their call-flop-cbet-% is valuable, as is their willingness to go to showdown.
But betting halfpot on a dry board isn't necessarily bad, depending on how it fits in with the rest of our strategy. Clearly OP is stealing a lot, and then making small c-bets can very well be the way to go.