I've had far more issues carrying regulateds around than mechs tbh - thinking about it, the two main incidents I can remember both involved Joyetech mods and both happened in cars whilst locked. First was an EVIC mini and you could have cooked an egg on the atty after, was only in the car for 2-3 minutes and I wasn't driving - I'll accept some responsibility for that one as it was in my side pocket, but all mods went in the inside pocket after that. The second was Primo 220 and was set at 120w, inside pocket and definitely locked - I was driving along a straight road and there was a horrid smell appeared in the cabin, thought it was maybe coming from outside then felt the heat, fecker had melted a big hole in the lining of my jacket. Really liked that mod too, solid, powerful and great chip with Arctic Fox on it, but the fire button was way, way too light so it was out the door.
I'll see about getting a lock doofer for my Runt Ark though, no issues so far, but it would be prudent to have one on it.