Mom hiding something

So my mom said she has never smoked in her life. But I don't really believe her. As long as I can remember several times a day she goes into our basement that we aren't allowed in and stays there for awhile. When she comes back up sometimes she smells weird, but not like cigarette smoke, but possibly some kind of smoke. When my uncle was still around and he came over (he's a smoker) they would both go down in the basement. Then one day (a couple years ago) I was trying to find some hair ties and found her journal I sort of looked threw it (I now know that is wrong) but one entry said 'smoked my last J' then I stopped reading. Recently I found a lighter and a stub of something it was like a white stick less than an inch long in the bathroom. I went outside one time and she quickly grabbed a jacket (that wasn't hers) and covered her hand, and the three something away in the outside garbage. Another time I walked into her room and again she covered her hand with something. Does this mean anything? I'm I just assuming things?