I'm betting the seal around your idler shaft is what's leaking and you're just seeing accumulation on that bolt head. If its not severe, I would just keep an eye on your oil level. If you're losing a lot then a tcase rebuild is in your near future.
Also the wire connected to that bolt is just a ground/bonding strap. Keeps electrical potential to a minimum between the vehicle's ground plane (the body) and the tranny & tcase.
Great, thank you. Yes very minimal oil accumulation. It's been sitting for the better part of 2 years. Start up every other week, drive around block. Oil and fluid checks were done today. T- case and Tranny levels were all good and cleclean.