Honestly, I noticed the same thing. I use a distance chart that someone posted, so the change in green speed is already accounted for (distance/hit wise).
I'm still reaching the greens in regulation, but my scores have dropped dramatically (err - gotten worse, that is). I was "routinely" getting -4s with a good smattering of -5s or better to go along with them. But as soon as I hit master, my range is now +1 to -1, with the occasional -2. I think just yesterday I did better than -2 for the first time or something.
Certainly not coming in to the green at the same place has an effect, longer tees mean different clubs to reach the greens. So making long putts is a lower percentage shot. But I have seen plenty of short putts just "choose" not to go in. I've ranted enough about that so will leave it there. :)
Back on point though, I agree, the change from Tour Pro to Master was startling score-wise.