I think that my (16) mom (48) found out I smoke

So I smoke, and I have for around a year and a half. Im not sure if its cause of the fact they dont actually pay attention at all to me but my parents have not noticed.

Well today I accidentally left the back door of the garage partially open. My mom happened to be in there and noticed it. What makes it worse is I left the Monster can I store my butts in right next to the door. Im hoping she didnt notice it, but if she did I need to know what to do if she confronts me.

Should I tell her outright or should I try and spin a lie?