What can it be ?

Today when I got home from work noticed a little what seemed like oil coming from the bead area of the rear tire. When I got down to check it out it felt lke water but had an oily tint to it ( if that makes any sense ) We went for a short ride the other day and all seemed fine. It is certainly not grease, the first thing I thought is I might have blown a seal on the rear bearing. What ever this is it does not run onto the ground like a real leak. Thanks Guys
Dave

:dontknow:Something you ran over that splashed in that area at low speed & surface tension held in place:dontknow: if it was tacky I'd say was bead sealer, some tire guys apply too much

My only other thought is if it could have come from the rear shock/spring.