It happens. I don't get it at all on treadmill but I do if I use the elliptical. If you're going to be doing a fair bit of running and never have been correctly fitted for shoes, you may want to look into pronation and buy a shoe based on that. You can look at the bottoms of your current shoes to get an idea if you over-, under- pronate. Or you could be normal. Good work man, you're really making so nice progress.
http://www.asics.com/us/en-us/pronation-guide
https://s-media-cache-ak0.pinimg.com/564x/9c/49/d8/9c49d88ffe0537bd4d292882c6e016d9.jpg
Dude thank you! I am definitely going to look into this. I don't mind dropped some cash on good running shoes if need be