IME, the facial expressions and ov-er pro-nun-ci-a-tion were a very sure sign that he'd had a few, regardless of anything he said to the contrary. If it was more than 'a few' it changed to droopy eyes and slurring.
After he didn't drink for a couple months, though, the behaviors, actions and the way he treated people, which I thought was just related to his drinking, were all still there and actually got worse, because he was having to cope with the stuff he usually avoided by drinking.
I knew, even if I didn't want to acknowledge it out loud, when he started drinking again, even though he hid the bottles, the eggshell walking feeling came on strong. I would smile with gritted teeth and tell everyone it was OK. I don't think I fooled any one but myself with that one. When he stopped hiding them, I knew life was about to get a lot more unpleasant. I'm not sure that makes any sense: me knowing that he was drinking, but not admitting it. And I'm not saying it's the same with your AH, but trust your instincts. If you feel that he's been drinking, you're most probably right.