Alarm randomly going off

So I just (yesterday) bought a used 2010 Prius and everything has been great so far. Today though, I was standing in my house and suddenly the alarm system went off! I grabbed the fob and hit unlock and it stopped. Looked up and down the street to see if anyone was running away or anything and nothing! Not even an acorn to have dropped on it... Was talking to my neighbor across the street who also didn't see anything, when it did it again. My neighbor thinks maybe the pair of gloves that had been sitting on it for at least an hour might have been the problem. I took them off about 15 minutes ago and so far so good. Is this maybe a sensitivity issue and I shouldn't let anything sit on the car? Is this a common problem? Figured this was the best place to go for help/advice/ideas