cost to replace front drl bulb. on 2007 Cadillac DTS

small light in front lamp assembly went out. dealer called it drl bulb. had to remove bumper and front light assembly to replace drl bulb. it was under warranty yet I would like to know cost if I had to pay for it.I case this happens again.

Asked by for the 2007 Cadillac DTS
that is normally around 400.00