For some reason, the Btn's raise on the flop "felt" more like AK-AT than a free-card play. His failure to 4-bet the flop though, made me reduce that to AJ/AT. As a result, the turn card slowed me down and I entered a check-call mode.

Notes:
- Relatively loose table (4+ people to most unraised flops).
- Not overly aggressive pre- or post-flop.
- However, Villain (Btn) is new to the table.

Live $5/$10 LHE.

Preflop: Hero is UTG with A , Q (8 players)
Hero raises, 4 folds, Btn calls, 1 fold, BB calls.

Flop: (6.25 SB) A , 7 , 2 (3 players)
BB checks, Hero bets, Btn raises, BB folds, Hero 3-bets, Btn calls.

Turn: (6 BB) J (2 players)
Hero checks, Btn bets, Hero calls.

River: (8 BB) 6 (2 players)
Hero checks, Btn bets, Hero calls.

Final Pot: 10 BB.

Am I playing too cautiously here?

BK.

I'm leading the turn, and calling down from there if raised.

yup

i probably do this, too, but if he raises the turn and fires the river, what can we really beat?
it'd be big odds by river but i dont see a weaker A or a flush draw playing this way

but yes, bet the turn. you'd hate to give a free card to Ax or a flush draw, even if you dont think he has diamonds

c/c turn, b/f river?

Or you could b/f turn.

I think your hand is very transparent and you have to be concerned what level the Btn is playing.
Against some players, you have to see the river

I think this is what scared me into check/call mode.

Now that I think about it, a bet on the turn, fold if raised (is that what b/f is?), and c/c river if just called, would probably have been best. This is the safest action given the range of hands my opponent might have here - AK-AT, flush draws, sets. I think only a very good opponent could raise me on the turn there with anything I can actually beat.

As it turns out, the Btn ended up having Q , 7 , which explains the aggression on the flop, and possibly the turn. Quite why he ended up betting the river, I'm not sure. I think I was lucky that the Btn bet out on both the turn and river, failing to take the free card I was offering or the free river check. So in the end, the mistake didn't end up costing me any more BB than if I'd bet out, turn and river. If anything, he may not have called the river bet, and I ended up 1 BB to the good.

BK.

It's hard to label him as aggressive based on the flop play given he had the pair too (as you noted); othewise, the obv note to make would be to c/c marginal hands HU OOP against this guy because he'll do the betting for you

As is though, he'd be really passive to not have played the flop that way.

I wonder what he thought when you cheked the turn. I noted your hand was transparent; but that really applied to the Preflop + flop play. Your turn check must've been odd in his eyes. He should have put you on "fearing a set of 2s or 7s or AJ" . He probably expected you would lead with AJ+ and were in with A9s-ATo or something like KK and you'd let it go now. Once you call him there the river bet is throwing money away.

b/f = bet fold, yes
OOP = out of position

Too passive. Keep the lead on turn.