Not having insurance, but still having to go to the doctor in the past year, I saw no reason to lie to a doctor about vaping. Or smoking. Keep in mind, I say here on ECF that I'm a proud moderate smoker. Last pack I bought was in 2013, and I still have some left. So, I smoke very little, but don't see myself as having quit. Thus, to insurance providers, I'd be a smoker with no need to get into details of what that means. To a doctor, it is a different story and the only story that matters I believe. I was honest with doctors about how much I smoke.
If I were to get insurance tomorrow, I'd have very little issue lying about smoking/vaping. I realize that could come back and bite me if I were caught in a lie, but after being bitten by both insurance companies and medical billing departments when insured (and not smoking), I just see it as a game to navigate thru. You take your chances, assess risks, and hope for the best. Man I despise health insurance. Whole system would be better if it would just go away, IMO. Stories you hear from how doctors were 50 to 100 years ago compared to how they are forced to be today, as they are navigating the game from the other side, is just despicable IMO. I really kinda hope Obamacare gets financially worse, and bankrupts a few insurance companies in the process. Then something else is put in place. What that is exactly is the trillion dollar answer, but what was going on right before Obamacare was not sustainable and right about now, Obamacare does not look good for the long term (by which I mean 3 to 5 years from now).
Sorry to bring up Obamacare, but I do see it as directly tied to OP and why OP was asked the question. IMO, it has nothing to do with doctor being concerned, and everything to do with insurance forcing doctors to ask that question, collect the information. As much as invoking Obamacare into a discussion could lead to hijacking of a thread, I'd like to be abundantly clear that what was in place before it, was IMO, worse but kept hidden/downplayed compared to how much certain people can't help but scrutinize the heck out of ACA. You got a better plan than ACA? Then put it forward. But going back to what was is very poor policy. Anyone that has a plan that gets rid of insurance as much as possible is one I'd support going forward. Then you wouldn't have to worry about rates going up because you chose to be honest with your doctor about what it is you do (i.e. vape).