Unfortunately, I would say if he was headed in the direction of your initial call, that this bird could have easily been called in for a shot.

A good rule of thumb, especially at sunrise, is to not make a move a minimum of 30 minutes after you hear the last gobble.

If I've been working a bird, I try not to move for at least 60 minutes. If the bird I'm working is gobbling to my calls, but moving off, it's a good bet that 1) he's with hens, or 2) he is hung up on an obstacle. These birds can be moved on, and if you get ahead of them, sometimes these are the easiest one to ambush...

Personally if I were you I'd go back to the same spot at sunrise, get comfy, and try and call that bird into my setup. From your description, with no alarm putts and no running/flying, that bird was not spooked and will act "normal".

Good luck...