Here is an answer from an online forum:
Join Date: Nov 2009
"i work for one of the main high street banks. We have been unable to supply Lira since Tuesday.
We have been informed that it is due to the Turkish government changing the supplier of who manufactures their notes, causing a hold up in supply outside of Turkey.
It won't be a problem getting them over there and we've been advised that by next week we will be back in stock."
.....reading through this forum until I got to this post, I was wondering if it was a ploy by the Turkish Government to bring more sterling into the country.