Formula foaming??

Just switched from Similac Pro Advanced to Similac Pro Sensitive and when I mix up the bottle there's a ton of foam every time. Like thick foam that sticks to the bottle even after he's long done. That didn't happen with advanced. Has anyone else had this happen with their formula? It doesn't seem to be causing any issues but I did freak out it first because I thought maybe I'd left dish soap in it or something lol (I didn't)