My motor had RTV on the threads when I disassembled it. Coolant had obviously leaked past the RTV because the shank of the bolt was corroded. The head of the bolt sealed against the cylinder head so no coolant leaked into the engine. Most of the bolts were like this, so it wasn't just an isolated problem with one bolt.

The teflon paste is the plumber's stuff. I wouldn't worry much about high temp stuff, the head bolt threads shouldn't see more than 250 degrees. I think the teflon stuff is mostly rated to 400 degrees.