I don't think having too much grease would cause a problem with the operation of the roof. If your roof has been dry and squeaking, it might have damaged or worn out slides (jaws) which are felt coated rubber/plastic.
Not too big of a job to remove the sunroof and inspect/replace them if you have the service manual. Bolt head locations should be marked with a paint pen before you remove them so you can get the adjustments back to original.