Man in Grees Bus uniform gave me 100 Baht and change?

I purchased seat 3A on VIP bus departing from Chiang Mai at 10:30 today going to Chiang Rai (purchased days ago on green bus app). I show up early and have a seat near platforms 20 and 21. Someone from Greenbus comes by and I show him my printed confirmation and he hands me a little bag with a little money (even has my name on the paper in the bag) I assume I need to give it to the bus driver or something but later after arriving in Chiang Rai, my friend picks me up and we go out for lunch. Later at my hotel I start unpacking at I empty my pockets and still have the bag of money.

Now did I unintentionally cheat someone?

The VIP bus is supposed to have only three seats per row and this bus had 4, and every seat was occupied. Did the reimburse me because they changed the type of bus? Still had my 3A seat I selected on the app, but the 3A on the app was first row single seat on right hand side, and now 3A was third row left side window seat.