Our routers only have white/amber LEDs. Are you using an AP330/350 as a router?
The color switching usually has to do with connectivity to HiveManager/HiveManager Online.
Heavy traffic load, or a slow wan connection/high latency can cause the CAPWAP connection to timeout. If this occurs the light may temporarily switch to green (indicating the Router/AP is up and ready for use, but unable to talk to HiveManager).
Fear not - everything will continue to work seamlessly regardless of connectivity to HiveManager.
Now you could check HiveManager when the LED switches to green, and if the device is still "connected" on HiveManager, there is a possibility that the AP may have a defective LED.
If that is the case, it could be worth opening a case with support for an RMA.