oil on top of the trans

I have a 95 golf 2.0 and brought the car to a body shop after a fender bender and the mechanic told me I had oil on the top of the trans. I looked at the car at his shop and sure enough there is oil covering the top of the tranny ( caught in all the crevases). He said it could be a blown head gasket and will check it out later. Has anyone had this problem before and could it be leaking from a line or hose or someting else. (Definitly engine oil) Thanks TOM