I am still relatively new to smoking meat and I currently have 2 corned beef brisket flats in my Pit Boss vertical smoker. They have been cooking for about 8 hours, but I just noticed that the temperature in my smoker was starting to creep up. I have it set to 250, but it has reached as high as 325 and is currently sitting at 310. I opened it up and noticed a pile of pellets in the burn pot coming out the top of the burn pot., as in the attached photo. Should I be seeing a pile with a flame on top of the burn pot, or should the pellets all be contained within the burn pot? Everything was vacuumed out before this cook and completely clean, and I am using a brand new bag of pellets. Assuming I shouldn't be seeing this many pellets, what would cause them to pile up like this?