its possible its factory.. i dont remember seeing any relays down there though, most of the relays are located in the engine bay and behind the kickplates in the footwells of both passenger and drivers side (most in the drivers side, but i think there are one or two on the passenger side)

you could start off by replacing it and see if that helps since its an inexpensive part, i picked a couple up at a local car alarm installer for like 5 bucks each