CC2560: BLE Adaptive Frequency Hopping: When are channels recovered?

Part Number:CC2560

This is probably a BLE spec question, but I'm not finding an answer to my question: When adaptive frequency hopping maps out some channels in a BLE connection, how and when are excluded channels re-incorporated into the channel map? In the lab with a PA, I see channels mapped out when expected (by generating controlled noise), but they appear to never be used again unless the BLE connection is broken and restarted. 

Thanks for any help!

Chas