AP 10 no longer has channel 13 since v8.307

Hi;

I have an AP10, for the last year it has been running on channel 13.

Two nights ago, I got the v8.307 upgrade.
Tonight I tried connecting to the wireless network, and I couldn't get a connection. (The power light was constantly flashing on and off)
I played around with the setting for a bit, and then tried setting the AP 10 to Channel = Auto. Up came the wireless network, and all was fine.?? Wierd I thought, and then I looked at what channel it was using, and it was set to channel 11. No big deal, but the wifi analyzer on my my android tablet shows I get best coverage on channel 13 or 14. So I tried setting it back to channel 13. There is no channel 13 any more. (Not sure if there use to be channel 14)

What happened to channels 12, 13 & 14..??

Trevor..