Little oil on the rear bumber

[Nicholas Menaker <72074.2716@CompuServe.COM>]

Well, during my 38 hour drive across the country, D.C. to L.A., after the first
few hundred miles, I noticed a bit of oil on the back of the rer bumper.  A
closer inspection of the rear end, there was some oil on the muffler and on the
rear trasaxle crankcase.  I almost started to s..t, thinking that I was going to
lose the tranny at the beginning of my journey.  The problem never got any
worse, (albeit, it did slow me down a bit) but now I would like to do a closer
inspection.  What should I check for?  I haven't been able to notice and other
leakage anywhere.  What sort of trans/case inspection can be done, and what
checks should suggest that this was just an annomaly?  I hope, I hope, I hope.

Thanks
Nick out