I've had similar experiences. Recently I found a WLW 117.9 that was not in the store on many earlier visits. Also in the recent past, I found old (cheesy gold medallion style) RHF and of all things a gold veined OWA that the store owner insisted just came in "this week" and had absolutely no dust on the bottle.
Hmm...time to re-visit all those stores I checked out last year. Who knows what may (re)appear?
"I distrust a man who says 'when.' He's got to be careful not to drink too much, because he's not to be trusted when he does." Sydney Greenstreet