I would definitely have the farrier come out and do a good "exam" to find out if it is his hoof that is causing the offness.
Did you check for any heat and swelling in his leg at all? This could also be a chiro issue. My TB will go "lame" on his front right, with no apparant reason at all. No heat, no swelling, just "off" on his front right - reaching short, etc, etc.
It's because of his hind end/hips/pelvis that goes out of alignment. I will have my Vet who is also a Chiro come out, and adjust him. *Poof* no more shortness or "offness" in his front end.
I can't see his feet to say yay, or nay, nor am I a Farrier....but you're on the right path having Professionals come out and assess the situation.