I've seen a number of stories here where people had that exact thing happen to them.Interesting... I've often wondered if that was the case with me, that it's just the habitual motion I'm stuck on. I also bite my nails like crazy, so I might be prone to oral fixations or something. If it was possible to pull off, I'd love for someone to cut my nicotine from my juice for a day without telling me to see if I'd really know the difference. We all think we can, but we all SWEAR we can tell Coke from Pepsi, too, and sure enough people suck at that as soon as you test them.
Basically they were vaping zero nicotine juice for some period of time without knowing even knowing it.
As far as I can tell, they often don't notice, and they often just decide to stick with it.