That's my guess. I've never had a decreased performance based upon how hard I push the button....and we have found that mashing the button repeatedly over time will damage the positive battery contact, and possibly even break it. If I remember correctly, it's made of spring steel...and does have it's breaking point. If you are able to get it to fire with a lighter touch like I can with mine, then I'm guessing that it is working as it should. As I said, my buttons travel very little before good contact is made and I can vape to my hearts content. The only decreased performance I have had issue with is when the battery has 3.7-3.9 volts left in it. ...at that point I am tempted to press harder, but it never helps.
Time to just put a freshly charged battery in. I do hope that regardless, you find a comfortable way to vape with the mini. The button top that Rob makes has helped others in this regard and may be worth trying....but I don't have one so I can't say for sure. Perhaps someone who has one can comment on this. If it continues to be uncomfortable, get a hold of Rob. He really does want you to enjoy it and use it pain free.
