strange burn, need help

the earth stove in my basement has been a trooper this year so far. however, i'm having an issue with way its burning. it seems to be burning from left to right. like all the wood on the left will burn, then work its way to the right. i have been loading evenly and even changing the way i lay the wood in, but nothing. its really annoying because it takes longer for the cat to light up entirely and i'm worried that i'm not burning clean and effective. this all started after i did a good clean out last weekend before the cold snap. my thought is an air leak (although i still have good control over the stove)... maybe the door gasket, but i just replaced it this year and it passed the dollar bill test. the ash pan is on the left side, maybe some ash got stuck around the seal and it isn't sealed? not sure exactly how the air flows into the stove, maybe i have an intake clogged? its really cold, so maybe a hard draft is doing something funny to it?

quick update. i did my own little "smoke test" around the door gasket and the ash pan. i basically ran a piece of smoking newspaper around those areas and it wasn't drawn in anywhere... so its not a leak in those locations, imo.
it must be a clogged intake or ash piled up where the air enters the stove...
on a side note, it seems to burn much more evenly with small splits. idk, maybe i'm being paranoid.