There is an increase of CO2 by being with your plants in an enclosed space.
I'm an outdoor guy, but I also blow smoke on my plants, but not weed smoke but tobacco. Insects don't like tobacco at all. I'm not religious about it, but if I happen to be there and be smoking a cig...I'll float it through the grow area.
Science has found that smoke triggers some plants survival mode....which makes sense.... where's there's smoke there's fire. Your plants don't know it's just you smoking a cig....they think a fire is nearby. I have no idea if/what weed response to smoke is, but it is possible.