Firmware update during activity

Last ride, after a break I restarted my device to continue my activity, but suddently my device starts a firmware (gps 290) update. After 5 minutes the update wasn't finished so I crossed my fingers and made a reboot. 

Some raised questions :

  1. Is it normal that a firmware update will be installed during a activity?
  2. Is it possible to disable autoupdate on a Edge 530? I