something leaking on inner wheel well

Hey guys, of course im getting ready to leave for saratoga lake ny just over 200 miles from my house for a club tourny. I was cleaning tires and rims on my 2008 stratos 201xl when i discovered something has leaked on the inside of the wheel well. I suspect its oil from my hubs, but they look full thru the plastic windows.? Although who knows they all look the same, a brownish color. It looks like a good amount on the wheel and driveway. I know nothing about these hubs?? Any sugestions on how to check on this?? Thanks