Same here!
I've had my 2012 13" MBA's SSD replaced about a month ago due to more and more frequently recurring system freezes. After firing it back up, it would take at least five minutes (no difference between leaving it off for that time span or trying again and again) for it to be able to boot up again properly. Within these five minutes I would get a folder with a question mark in it, which basically tells you no boot device found.
When I tried to back it up, it failed even more frequently so that I knew it had to be the SSD. I kinda got everything important off it, but it was a pain in the ass, since it kept freezing every 5-10 minutes.
Got my SSD replaced easily on warranty.