Am I misremembering, or did I hear that valve covers leaking is common on FB20 engines? I have a friend with a 2014 Crosstrek and there's a fairly small amount of oil on the floor of his garage below the right side of his engine block. The grounding strap on the right side of the engine appears to be saturated in oil and very dirty. And you can see a little bit of an oil film spread out on a part of the frame right below the right side of the engine block. Sorry I don't have any pictures currently.
He said he accidentally hit (fairly slowly in a parking lot) a hitch that was sticking out a few weeks ago, and neither he nor I noticed oil on the floor of the garage until the past few days. It seems unlikely that a slight bump that only slightly cracked the front bumper cover and didn't do anything more would have damaged the engine block or anything in that area enough to leak oil, right? My first and currently only suspicion is a valve cover leak, and the timing was just a coincidence.