You have to remember that when a dealer does a head gasket change on a low mileage engine, they usually will NOT machine the head to make sure it is flat. They simply remove the head by cleaning the surfaces and then reassemble. The other issue is that the employee with the cheapest labor price will do the “leg work” cleaning surfaces etc, which can easily lead to substandard work.
Having said all that, there are of course exceptions, but it seems that this could be one of the cases mentioned above.
The other thing of note is that I suspect the engine may have had an oil “weep” (a small dark patch covered in dust, but no drop of oil anywhere). These types of “leaks” as reported by several members on this forum are usually best left alone and simply cleaned at every oil change and monitored for change. Usually they never become a trickle and once you “open the can of worms” trying to fix the problem, you will never be satisfied.
Sea grass
