Fired from Walmart

I got fired from Walmart a couple days ago. they fired me for stealing, I had only been working there not even 3 months yet. Early on someone saw me get soda from the Subway using a water cup. They talked to me and I never did it again and then like two weeks ago I think it was. I was at the self checkout and after I paid and attendant had to come over for some reason she just scanned her badge and said I was good to go. While I was getting all my stuff I saw a $20 bill in the cash change area and I took it thinking it was mine. I paid with card I just thought something messed up and it gave me $20 of my own money. Well they used that and the soda incident to fire me for theft. I just want to know if you've heard of anyone else getting fired over something all small as this.