Screw punctured tire in parking lot

So as I am leaving work yesterday on my way to Cutter for service on my M3 I see the construction workers looking for something on the ground around my car saying "I know I dropped one, what happened to it?"

I didn't see anything and wasn't sure what they were looking for. I began to drive away and I heard a clicking, I knew something was in my tire but I couldn't find anything on the sidewall. So I drive 20 minutes to cutter and all my tires look fine so I figure its mechanical. My service rep calls me 30 minutes later and tells me I have a screw in my tire and need a new one since it is too close to the sidewall to fix.

Personally I think I need both front tires replaces since I have 15k miles on them. I called the property manager and they said their workers told her they aren't using screws :thumbdwn: and she therefore does not feel the property management company has any liability in the matter. Has anyone else been in this situation? Any suggesstions about what I should do?

Thanks,
Iaian