That's usually my first thought as well, but since he says that it doesn't change when opening the bleeders, it's likely not residual pressure from either a check valve (which he doesn't have) or a misadjusted rod. Of course, those pesky rod adjustments cause all types of harm, it just doesn't sound like the case here.
In fact, it doesn't really sound like brake drag to me. Sounds normal for older design disc setups.
And a wheel that's getting warm is not a warning of anything. Only a wheel that's hot is a sign of something maybe worth looking at. But only "maybe" as normal hard braking can make a wheel hot as well.
As can an improperly adjusted wheel bearing.
But warm is the norm.
If you can turn the hub and rotor by hand without the tire and wheel mounted up, it's not dragging very much. That 3/4 turn movement is also not out of line. Sure, it's not truly free-floating, but these calipers don't fully release like modern calipers purport to.
My Ford disc setup can sometimes leave the hubs and wheels cool to the touch after a drive, but often enough there's a little residual warmth in them as well. Never hot like some, but certainly warm. Don't know if the Ford calipers are expected to have the more, or less, or the same amount of drag as the GM style, but I do hear them rub slightly. Can't remember how much the tire rotates after letting go, but I bet it's not much different.
And like was said, maybe they'll still wear in a little after some use.
I'm not trying to talk you out of being cautious and keeping an eye on things. Just trying to say that what you're describing is not really off base for what I would expect.
Maybe others have different experiences, but that's my opinion anyway.
Paul