I picked up my Elantra on Saturday, and the alarm had already gone off at random a few times by yesterday. I also noticed that a few times, the lights did not flash after pressing the lock button on the remote...which would normally indicate an open door, but they were all closed. I googled and found this post. Made an appointment and took the car in this morning. It was the hood switch/sensor that needed to be replaced as others have said.
regatta blue - PZEV - automatic - popular equipment package - carpeted floor mats - mud guards