Possible that some were saved, but not all the millions printed. Lately, I've begun to see more and more 1993/1995 $20 notes than before, so, it's surprising that there was a shortage of them back in 2011.
I will say that 1995 $20 notes have definitely made a resurgence and appearance this year as they are turning up in teller's mute piles with relative frequency. Here is one such note: This note stands out as it was printed towards the end of the series right before the design transition took place and has seen a good amount of circulation. It's also interesting in the sense it has clearly been stored in a book or some such object for quite a while and seems to have recently been discovered and used: Not a keeper but it's still neat to ponder where it's been and how long it was put away before being found.