Opinions?
Not at all. Its a vent/overflow. I have owned 3 S197 cars and they all do it. Not to mention, I have taken them in for it and the dealer says its only a concern if its excessive. And the one on my shelby was leaking like a siv when I would pound on the car. 100x more than yours. I know there is also a TSB for it, where they put a longer vent on there so the oil cant get out. But there is going to be some that comes out from that vent. Better there than around the diff cover or rear seal. Thats the point of it, to relieve the pressure. No worries man.