Speaking as a mechanic...if you are sure it is not left over residue dripping down, and the fluid level is indeed dropping as it sits, call the service advisor and let him/her know what is happening.
Sometimes if P/S fluid is not cleaned up properly, it can drip from the surrounding area for some time.
If the fluid level is going down, they may not have a line tight or a bad pump to body seal. Probably something minor which they will be more than willing to repair under warranty. Give them a chance and I'm sure they will do their best for you. They want to treat you right hoping they will retain you as a customer even after the warranty is up on your car.
Hope this helps.
