Two weeks ago I visited Houston Museum of Fine Arts in Houston on Friday afternoon and parked at the bike rack in the sculpture garden. Less than an hour later I came out and had a flat front tire. It's been a while since I had a flat, so I accepted that's the way it goes and walked my bike to my next destination and changed tubes there. Tube had no puncture so thought it was a valve problem. I didn't have a valve stem cover on.
Two weeks later, this last Friday - exact same time of day, different bike with beefier tires, same thing. This time there was a small hole in the tube, but I did have a valves stem cover on. Harder to be philosophical about it at this point. Security said they looked at camera and didn't see anybody.
Weirdo that hates bikes, thief hoping I'd leave it there long term, or just unfortunate coincidence. It's been about two years since I got a puncture, and the reasons are usually obvious.
I won't be parking there again. I'm only posting this in case there is a pattern beyond my own that someone might recognize.
