How Did Gollum Lose the Ring?

[Boo Radley]

OK. That much is known from the stories. (And thanks for all the quotes. Very thorough work on your part.) But, I guess what I'm trying to ask is what transpired in order for Bilbo to happen upon it? Was Gollum wearing it away from his island and it slipped off his finger? I can't buy that, because surely he'd be aware of that happening. And even if he somehow was oblivious to it no longer being on his finger, why would he rush back to his island to look for it? Well, maybe I can understand that. Who of us hasn't gone back over the same ground numerous times in the vain hope of finding something we've lost, even when we KNOW it aint where we're looking?
"Honey, you've looked for your keys on that end table a dozen times! You know they aren't there!"

Did he then go back to wearing it in a pouch and it fell out?
Did the Ring grow little, tiny feetsies and go for a stroll on it's own?

Maybe it did cloud his mind a bit, so for a short time, he wasn't obsessed with it. But I wonder how long it was out of his possesion before Bilbo happened upon it.

I know it's not really important, but I just started wondering how a creature so consumed with something could not be aware of it's absence.