If it's just a seep without a drip, I'd personally leave it alone. Don't fix what ain't broke. IMHO, if you had that much oil spraying about under the hood, it's entirely possible that the oil "seeping" from the diff is actually from all the leaks and not actually the diff.

If it were mine, I'd have the engine mounts replaced, then go in there and clean everything up with degreaser and give it a good bath, then watch it and see how much of a "seep" you really have. If it's just a "sweat" of oil around the gasket, leave it. If it's enough to form a drip, it may be worth having them do the reseal. 2008@ 70K miles seems awfully young to have a diff oil leak big enough to worry about.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]