Checking base timing with a timing light

[Onefast99gsx]

I'm checking over some things to rule everything out. So last night I checked the base timing with the timing light. I did the GND Timing function in dsmlink. On the timing belt cover I seen what looked like a 10 and a letter T. My dot on the crankshaft pulley sits next to the T with the timing light dial set at about 7 or 8.

The dot will sit there for a few seconds and then shoot up a little bit(1/2" or so) and then come back down and sit next to the T again. Is this normal for it to dance around like that. Is that just the change in idle? It was idling between 950 & 1050 during the test.

Thanks.