I called my selling dealer to make an appointment to have it checked and asked if they had any other type of complaint. I got a call back within 5 minutes and was told to clean the oily liquid off the windshield, that it was normal and GM even has a sponge behind the rearview mounting plate for just such an issue.This is my fourth Tahoe and yes this one has more bells & whistles that the others but I've never had this happen before. Has anyone else experienced this before and what was done to correct it?