alosso:
Hi Yancy,
I have experienced this for a few months already. No explanation, no remedy available. And, the speed-up is variable.
I'm an off-ding putter which is good - I can react on the grid speed. I use the faster speed to determine the putt line.
I commented in another thread about 3 weeks ago, on the 'saw-tooth' pattern of dot speed. Over a period of 8-10 seconds, the speed of the putting grid moving dots slowly decreases to a 'minimum', then the speed quickly jumps to a 'maximum' indicated slope.
However if you switch to Chip shot mode, the moving dot speed is constant and about equal to 'max' indicated putting slope shown in putt mode. Using the maximum observed speed is a good idea.
There's a reason you see top players setting up their putting line with a chipper in their hands, then switching to the putter to make the stroke!