Ah okay, I know it also happens sometimes when the food is too big as well and they push the excess out. I'm not sure if that's WHY they do it, but it's just what I've observed.
Aqueon Betta food is not healthy food at all. If you want him to really get healthy and happy you should try to find New Life Spectrum Betta or Small Fish Formula and/or Omega One. Both of those foods are very high quality (but won't break your bank) and sooooo good for them! One way to tell is look at the first three ingredients of your food. Look for things called fillers which consist of Wheat, Corn and Soybean. Those are fillers and things your Betta can't digest well or at all.
Omega One has no fillers in it's first three ingredients, making it one of the best foods to give. New Life Spectrum easily ties or places second to Omega, it does have one filler but makes up for it in the fact that it also has spirulina and garlic. Garlic is a natural anti-parasitic food and Betta's absolutely love it! Not saying that this is some magic to make your fish never get internal parasites but it aides in preventing it for sure!
So those are just some things you can get to further help your fish and I guarantee that you will see an amazing difference when he starts eating this food after a while! He'll color up, most likely be more active and so on! NLS is also a much smaller pellet which will be easier for him to eat and digest!