It sounds like he is over reaching, I used to look after an anglo arab who used to do this alot. Not to the extend that he would hurt himself but it was enough to make us concerned. We got him some over reach boots which kept coming off in the mud so we also got him something ( I can't remember the name of them for the life of me) but it was like a horse rubber anklet if that makes any sence. It was made of rubber and it went around the hoof just before the coronet band/hoof wall. If anybody knows what im talking about please let me know, its bugging me that I can't remember the name of it. But we got him that and it would stop him from hitting his front feet when walking, after a couple of months he got into the habbit of not over reaching as much. I think some people also use what we braught for horses that paw. Sorry if this is hard to understand the way I tried to explain it.
:~: A Horse Is An Angel Without Wings :~: