Shoppers Drug Mart complaint: Fired after one day training for supervisor

I applied at the 10th st W Owen Sound shoppers for the supervisor position, I had worked at the Hanover Ontario location and the Owen Sound store called them for a reference, I got rave reviews from management there. I went in for my first training shift, the cash supervisor was not there, so a cashier was training me. She was upset because I already knew how to run the till, (I was a supervisor for SDM before) and by accident I had gas, and by accident a fart slipped.( true story) and I adjusted my bra strap as it was falling down. She told me I could go home as it wasn’t busy at that time. I asked are unit sure? She said I did a great job and see you tomorrow. I got a call today from the supervisor that hired me, that because I passed gas I’m not fit to work there and they terminated my employment. What do you make of this? The cashier was not happy at all and obviously didn’t like me fir some reason.