Replying to Caught my mom smoking weed

My mom has always been the typical "Don't do drugs. they're bad for you" type. She always told me when I was a kid to stay away from them. Ive heard from family members that when she was young, she liked to party a lot. I can't really see it in her as she isn't much of a social butterfly and I've never seen her drink. My parents are always going to concerts though. Usually they'll go to a Paul McCartney concert or something, and then they'll come home st like 1 and go to bed. So last night there was a Billy Joel concert in town. My parents went out and I went to work my evening shift at Dairy Queen. Normally i get home around 10, but I went to my friends place for a little afterward. Got back at my place around 2 in the morning. I didn't want to wake them up cause I knew they'd be pissed at me for coming home so late. I decided to walk around to the back door. As I was in my backyard, the scent of burning ganja smacked my nostrils. I heard muffled voices. I turned the corner thinking it was my brother and his friends, but it wasn't them. It was my mom and her friends. She was standing right in front of me smoking a J. I made eye contact with her bloodshot eyes. Her pupils constricted and she said "MICHAEL WHAT ARE YOU DOING UP SO LATE". To which I replied "Sorry mom I was at work and I didn't want to wake you up" She then yelled at me "GO TO BED. IT'S LATE". I had a shit eating grin on my face at this point. I asked her "Mom are you smoking"? Her face became as red as the kush embers. She exclaimed "THIS IS A CIGARETTE. I'VE HAD A VERY STRESSFUL NIGHT. NOW GO TO BED". And I went to bed.


Sooo like what should I do lol. I was thinking just buy one of those Walmart drug tests and just set it on the counter when she comes home.