Are you sure oil didn't drop down from somewhere else? I thought the typical rear main seal leak only shows up at the bottom between the engine and clutch housing.
On my Quota, it was leaking a decent amount (several spots on the back of the engine), and all that oil dripped out the tiny drain hole on the bottom ... the spots you pics are showing stayed completely dry on my bike.
Have you pulled your airfilter and looked inside the airbox ... dry? or oil in there?
I've betting it is from something else.