Baby palm (stopped by security)

For the second time in three days, I've been told not to take photos.

I parked my car at my work building's garage and walked outside to get a few pictures of anything before work. I work late, so the sun was setting. Great light. I took a few dull pictures of a baby palm tree. Someone drove by, pulled out of the parking lot and stopped in the street in front of me. I didn't think anything of it.

But then a minute later, a security guard came out and shouted, "No pictures." Not this again. I turned toward her, and she recognized me and said someone called. She said they have to check things out when people call. Very weird. I was in a parking lot (actually, I was next to the parking lot in the plants) and simply taking pictures of bushes and other plants. Why would someone call security?