MachtigAvant (v3.0)

and I was on my cell phone at the time! :-0 But I was having serious rim trouble at the time (running on square rims) and just had filled up air and was on my way to rim pro to have them straightened. (Just my luck they pop on my way over...)

S4mig@PEB tuning

pothole sir.

WECoyote-SuperGenius

no evidence of fod. the town has been doing a major road reconstrution project in my neighborhood. spoken to a few neighbors and quite a few have had punctures too. appears that the gravel they are using on the new road bed is extremely sharp.
need new tires on wife's car and want to replace my repaired ones, but will wait until the road is finished.

S4_Cinci (I S'edTFA)

I have a similar mark on my tire. It isn't fatal, but just cosmetic. Couldn't figure it out for a while, but finally realized it was something I had "hit". Turned out to be an old railroad rail that runs thru my work parking lot - they cut through it instead of removing it. This left an exposed piece of rail with a relatively sharp edge that is raised 1.5 to 2 inches above the pavement surface. This is located at a spot where you have to turn in the lot. I matched this up for proof - I must have turned too close to the exposed stub one day and the edge caught the sidewall and made a nice clean tear in the sidewall.

This is a long explanation, but trying to say you could have turned next to one of those metal plates they use to cover in-process road repairs or something like that and never even noticed it until your tire suddenly lost air pressure. I know I would still be wondering WTF happened to my tire if the cause wasn't in my work parking lot. Remember, the simplest explanation is usually (though not always) the correct one. Hitting something like I described seems much more likely than vandalism on just a single tire. I would think if someone is pissed off enough to slash your tire, there would be other damage as well. Hope this helps!