That cotter pin in a hole is designed to keep the hole clear to allow fluid to drip out.
Usually found bottom of bell housing on clutched tractors.
Over fill is one possibility but another is a damaged oil seal that allows leakage.
Checking fluid level is best bet and there is always the possibility that what you see is a longtime accumulation that simply suddenly decided to 'let go'.
If the fluid level maintains itself reasonably well, just live with it.
If it is hydraulic fluid then you actually have a lot in there B4 you cause damage, and besides the FEL will starve when it gets too low without creating serious damage. (FEL equipped tractors generally share the transmission fluid hence a lot in there)
The concern would be if you are hydrostatic as starving the pump could prove costly.