From my understanding, it won't ever hurt him, it's just unsightly and would lower your score in certain shows. But it wouldn't hurt to have it looked at to see if it's fixable. =]
I see paddling most often in saddleseat horses, likely from the soring and the super long toes [which is why I brought up his feet], but since he's a TB, I doubt he was saddleseat trained, and could just have a "hitch" in that leg. Good luck!
EDIT: Err, is he a TB? You said OTT, but not OTTB. O_O THat make my last paragraph inaccurate.