It has never, nor would it ever, occur to me to ask a store to hold fabric - amazing concept....
I did call JoAnns once and asked them to hold the one remaining machine tote they had - and I picked it up as soon as I could the same day - it's an hour and a half drive for us to get there...
Possibly if you had been scouring the 'net for a particular fabric and found a store locally that had it?? Call and say hold it til I get there sort of thing?