Smoke in firebox

I ran 12hrs yesterday on a brisket.... it was amazing.
Towards the end my hopper was pretty empty and I could see smoke coming from the hopper. I moved the pellets around and nothing felt abnormally hot. It appeared the smoke was just backflowing through the hopper? Is that possible?
Please advise.
Towards the end my hopper was pretty empty and I could see smoke coming from the hopper. I moved the pellets around and nothing felt abnormally hot. It appeared the smoke was just backflowing through the hopper? Is that possible?
Please advise.