Looks like comcast has reset / upgraded their local system - like they were threatening to.
Noticed it when Radio Paradise just stopped tonight, and went through the whole turning it off and on again shenanigans (including using google DNS for a while).
Before
After
Speedtest.net is misbehaving, and the San Jose comcast server is saying starting test in 18500 seconds ...
So take the above ( esp ping) with a pinch of salt. See if things have changed in the morning