Mine turned out to be the exact same thing! Been chasing it for 8 months.... while I had the car down doing the suspension I decided to replace the grommet and the PCV valve, turns out it was blowing out of there just enough to pool at back and drip down. For anybody out there chasing the passenger side oil leak, check this, may be the issue - or at least one of them, lol. It can easily look like a valve cover leak, too.Update 5 years later. It was oil blowing out of the PVC seal in the intake. It would fill up the top of the intake at the back and then drain down passenger side head where it meets the block and that's how it was ending up on bottom of header flange. Replaced grommet and no more oil.