That usually means the PVR needed to do something and it's possible all the HD feeds were in use. Nothing is dying or needing an upgrade, aside from when your remote area finally gets faster speeds to allow more HD feeds.
I had some strange router/PVR anomalies last night too. I thought it was because I unplugged the PVR my mistake earlier in the evening when configuring some new hardware.
Perhaps there was some upgrade sent across.