Hover found a stale entry in the parent .net zone and removed it. Google flushed their caches for mailroute.net, and google DNS servers are properly resolving the mailroute.net domain once again.
*This issue started around 2:00pm pacific and was resolved at roughly 4:30 pm.
We are working with Google and Hover.com engineers to determine what is causing Google's public DNS servers to fail to resolve the mailroute.net DNS zone.
We suspect it is due to stale records in Hover's parent zone for .net, and hope to have this resolved quickly.