The Games Workshop webstore earlier today had a very brief few minutes today where Necron models were showing up out of stock, and then 15 minutes later restored. The rumors of late are saying that Necrons are next, and if so, there may just be some updates being prepped on the webstore for a future release.
Please take these as hints and rumors. By the time I went and checked, everything was back to normal.
via a reader on Faeit 212
Just noticed something a little odd... looking on the GW uk site, EVERY necron model is showing up as out of stock (as of 1740 uk time)
... and 15 mins later, everything has popped back up again...