I would venture to guess that there is some kind of glue between the layers of the strap that dissolved in the bath.
As for what to do about it, I really don't know. Some kind of sticky substance remover like acetone or Goo Gone might help...or it might make things still worse.
So sorry this happened!
Thank you, Catbird9!
This is such a mystery to me as it's just the top 14" of the strap that's worn and sticky and a bit thinner than the rest of the strap.
I have several Coach Sonomas and the straps are so thick & sturdy.
The bag itself is in EUC - can't figure out how that poor strap got that way!
Don't think I'm ready to do the acetone/Goo Gone route just yet....
I think I'll wash the strap one more time, and ponder what to do after that.
If I come up with a solution I'll be sure to post it.