Just flew MSP > MKE Flight 600.

I booked a M Class ticket last night since I missed other flights and United wanted $250! This was $180.

So I get to ticketing get my BP its seat 10D, I get to gate and there is a giantass crowd of high schoolers on this flight, They start boarding and after zone 4 is starting they call me up hand me new BP seat 2D! Not sure how it happened but I will take it. I have zero status with AT and have 1 credit from a Priceline flight back in Dec.

I assume I got upgraded to due ticket class?