LED "signal" loop

Gooday Folks,
I have 20 photons out in the field for the last 4 months.
All are running 0.60 and this morning all were flashing the led as “signal” constantly.
All 20 were reporting events over the Wifi and running their programs OK. Breathing cyan was restored with

  1. Power off reboot
  2. IOS app signal button, after the 10 sec default on
  3. Web IDE, on signal button then off
    So no harm but unexplained mass behavior.