My gelding does this too, it could just be a thing that they like to do. I just had his teeth done recently, vet said he was good to go. I also wet down his grain so it is a mush. He likes to push his feed arond his bin with his nose, dig to the bottom and push everything to the sides for some reason then eat from there. He ends up tossing a lot of it out of his bucket and drops it when he chews as well. With him I just think it is how he eats. I agree that getting a mat or a hanging bucket would be best, or maybe even doing both. Good luck.