checking timing with timing light

[SoCal250]

Decided to double check my RD125 timing with an actual light. I'm using a standard Craftsman inductive timing gun.
Static timing was initially set with a dial gauge and quadruple verified. It's right on 1.8mm BTDC on both cylinders and I made sure the factory pointer was aligned.

With the light and engine at idle (or revved up to about 3K) the mark on the rotor seems to bounce around a little. It's not perfectly steady, moving erratically a little plus and minus from the pointer, and happens on both sides. Is that normal? I thought I recall seeing in Chuck's videos that the pointer and rotor mark were always steady/stable.

[Striker1423]

My guess is that jumping is either point dwell, or a temporary flicker in the induction pickup on the light. They aren't always aperfect when reading pulses.