Gearbox oil leak

[Misterblu]

Yesterday looking under the car i have seen a small oily spot.
So i wanted to deepen. i disassembled the protection under the gearbox and i saw this drop. It seems like a small leak, because the protection was not very dirty





Is this failure to be considered serious or i can stay peace of mind ?
has this happened to any of you ?

Thanks in advance for advice