Rachio 3 occasionally using 8.8.8.8 instead of DHCP assigned DNS server

Hey all,
For security, I force all network devices to use a DNS server I manage. I block access to other DNS servers (protocol wise).
Rachio 3 is working fine as far as I can tell. And it is making queries appropriately for NTP and AWS, but my firewall has blocked several attempts from Rachio 3 to make DNS queries to 8.8.8.8.

With some tinkering, I could determine what name it’s attempting to resolve using 8.8.8.8. But I thought I would ask here first.

  1. Any concerns about getting updates, etc?
  2. What function or service is going rogue here?

Cheers!