K46 leaking oil from vent cap

Today I was checking a few things out on my X300 (as you may have seen in a post about my tractor going slower than it should) and I noticed that it seems to be leaking oil from the vent cap on top of the k46 transaxle. I washed the tractor last Saturday and know for sure it wasn't there then because I would have noticed it. The next day I did get stuck while pulling a cart of wood up a little incline that happened to be all mud under the leaves. I tried a couple times to make it up the incline by backing up and going forward again with no success. I wouldn't say I was beating on it by anymeans. I finally unhooked the cart and was able to drive out and go get a neighbors 4-wheeler to get the cart out.

I put the tractor away shortly after and don't recall looking it over so didn't notice anything wrong or a leak. This is the only thing I can think of that may have been the cause of this. I wiped it with my finger and nothing came off. It has 230 hours on it and to my knowledge the oil in the k46 has never been changed. What do you guys think after looking at the picture? Definite leak? could the vent cap have a bad seal or something? I guess it's time to change the oil in the unservicable transaxle.