Keep getting asked to re-pair BT

I am using a Nexus 5 on the latest android build, with a fenix 3.
If I go to the edge of bluetooth coverage, the fenix prompts to repair to the phone. The passcode appears, and I get a notification on the phone to pair. Cancelling these causes no problems and the fenix reconnects fine when back in range. This is obviously a bug, and it's annoying as I walk around the house and garden without my phone in my pocket.
Anyone else experience this? Garmin - known bug?