Since you say he's not sore or lame and been doing it since you've had him, I would be bold enough to say it's a manners issue. He's just being rude and leaning on you.
To progress with this, you can saddle your horse, and take a large, soft cotton rope, and tie your horse's foot up to the saddle horn. Tie it up to where you would normally like to hold it to clean or pick it, and leave him to stand tied with the leg up until he stands there and relaxes with his foot up without fighting the rope. Most likely, he'll fight with it for a while. That's good. He's testing his limits. When you come back to him, untie from the horn, but keep the rope on the foot. Do your picking. If he acts like he's going to trip or lose his balance, IMMEDIATELY tie the foot back up to the horn until he relaxes, then go back to picking. Do this back and forth with all feet, every day you ride, until he learns that it's easiest just to hold them there for the few seconds it takes you to pick them rather than stand there all day long with his leg tied up!
But, once he gets it down, and KNOWS what you want, you shouldn't even have to break the saddle out yet. My horse knows better, and if she gets lazy for those few seconds it takes me to pick her feet, or the few minutes it takes me to trim her feathers, a smart and cupped slap on the belly straightens her up!
Last edited by westonsma; 06-11-2010 at 10:58 AM.