What you are seeing is likely the dowel pins. Since bolts are too sloppy to position the cover, there are two ground pins pressed into the block. The timing cover slides (somewhat tightly) over these pins. The snug fit keeps the alignment where it should be. The tight fit can cause a problem when 16 years of crud accumulates at the end of the dowels...keeping the cover from sliding off. Pop the cover back into place and clean off the end of the dowels. I prefer scotchbrite, but sandpaper or steel wool will work just fine.