Highly doubt your HG is leaking..unless you broke the new one or did not torque the head bolts correctly in the right sequence...

It could be a warped oil filter gasket on the housing. I have the same leak pooling there and onto the damper...same places as you that just started when I changed the oil about 500mi ago, so I am thinking it's gotta be the gasket as I have retightened the filter about 3 times now and it is still leaking trails of smoke behind me on the freeway.

You can always get some dye to figure it out. I will probably do the same to make sure its the housing.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k