It depends on a few things. What type of anti-depressants are you taking, OP? Quitting smoking (vaping) and using an anti-depressant can a great deal to do with one another.
Consider this: What happens when you smoke, or use nicotine? A number of things, of course. But, specifically, let's talk about dopamine, a neurotransmitter that makes you feel fantastic. When you use nicotine, dopamine levels increase in the brain. When the levels decrease, the body wishes for more, and voila, addiction.
http://quitsmoking.about.com/od/nicotine/a/nicotineeffects.htm
Now, let's think about anti-depressants. Some have very similar effects to the brain as nicotine, in that, it causes the body to release more of the neurotransmitter dopamine.
Antidepressants and the dopamine connection
Now, let's talk about the combination of both and the possibility of why things are happening as they are. Do we have any actual studies that show exactly how much nicotine is absorbed into the body via vaping as opposed to smoking traditional cigs? If so, I'd be interested in reading it, for sure.
However, if not, all we can do is assume, or make educated guesses, right?
Let me just throw it out there: If the body notices an change, and the change is semi-permanent, the body will respond in like - (for example: smoking or vaping or using anti-deps = release of more dopamine, the body will eventually believe that it has more than it needs of the neurotransmitter and cease, or reduce the amount being made).
So, I ask again to the OP, what anti-deps are you using? What changes have you personally noticed?