There has been a minor bug fix update released (version 7.7.8/7.6.8)
http://www.macrumors.com/2016/12/20/apple-airport-base-station-firmware-update/
You won't see it unless you open Airport Utility and click on the Airport/Time Capsule icon to bring up the details window which should now have an Update button to click on.
Initially my Airport Express failed to update then vanished from the network. I really must replace it's Ethernet cable: it doesn't always seat properly in the broadband router's Ethernet ports.
After rejigging the Ethernet connection the update went ahead OK.