Weird timing given how bad he was last night, but I'll take it as a positive sign that Belichick either doesn't think he was as much of a problem as he looked or doesn't think it'll be a recurring issue. I was really impressed with how Van Noy integrated into the defense last year, so I'm nowhere near writing him off or anything - he had an alarmingly bad game, but it's just won game following a string of solid performances, playing next to a mike who was not ready to be in there.
Although Freeny did get a similarly timed extension not too long ago, so who knows, this could be the same as that - just paying a premium to establish a base line of performance and hope that you can find better players to surpass it.
If I'm Belichick, even if they already had this extension agreed upon I probably would have held off for a week and said "you'll get your extension next time you play a good football game", but admittedly that would be a spiteful move that could easily backfire and that's one of many reasons why I'm me and Belichick's Belichick and he's the GOAT and I'm just some random guy on the internet.