My mech. says its a glitch that will happen. Mine has done it after oil changes for about 15 min. and then goes away. Just check the level and as kernith said, listen for a clanking valvetrain because then you have a serious problem.
By the way, if you have the 3.2 V6, its a tuff little motor. Mine sprang a leak without my knowledge (oddly all the places I park regularly are asphalt so I could see the stain) and my motor ran for an unknown amount of miles BONE DRY! I know, I know I cried too. Oh, guess what, NO OIL LIGHT! The the tip off was my motor running a little warmer than usual right before my oil "change".