I noticed when I shut off the engine this evening, there was a gurgling sound coming from the roundish part located next to the IP (I'm pretty sure) on the drivers side of the engine bay. The part has two tubes coming out of the top and is labeled "VAC" and "OUT". The sound lasted about three minutes. I haven't noticed it before, but that doesn't mean it's hasn't doing this for awhile. Is this something to be concerned with or normal? I haven't detected any change in the performance of the car.