I have a super humid garage. Due to the way the land lies it just gets ridiculously wet in there. I had a car with a semi-failed ignition coil and on really wet days it would misfire terribly before warming up. If you ever parked it anywhere else it would be fine.
Now my newer TDI has a slight hesitation sometimes after being parked there, possibly the same cause, although obviously problematic for different physical reasons since this engine has no ignition coil. Maybe the injector tips foul slightly if the first fire if day is super wet...don't know. I left town for a week, drove all over Ohio and Kentucky and didn't see this problem once.
Btw, the Miata starts fine, no issues relating to this.
[EDIT] Sorry, this was meant for the mold/humidity thread.