Here's the background... 2005 3.0L E53 98K miles (stop & go, plus we live in hilly area)

Few days ago the X5 starting running rough and threw a P301 code. We pulled plug #1 and it was pretty much soaked in oil. Cleaned up as much oil as possible and inserted a fresh plug and that cleared the problem temporarily. No code and the engine runs fine.

Yesterday we pulled all 6 plugs. #1 came out clean. Of the remaining 5, 3 came out soaked in oil and 2 came out with slight caked on dry oil residue. We replaced with a set of 6 fresh plugs. The plan is to pull the plugs in a few days and inspect for oil.

He says the head gasket is leaking. He replaced the valve cover gasket approx 2-3 years ago. He says if the VCG was leaking we would see more oil in the spark plug tube before we pull the plugs and we'd see oil higher up on the spark plugs.

Does his diagnosis sound correct? If so, is $1400 a fair price?

TIA for your advice.