Tchara,
I have observed something similar with my signalstat 900.
I use a flasher designed for LED's (which I presume means it does not rely on certain resistance in the lamp circuit to have a correctly timed flash rate). The flasher module is an AMAZON special "CEC" brand meant to use with LED lamps. (I use LEDS for my grille, and regular filament bulbs in the tail lamps).
When I signal, the indicator lamp flashes normally in the signal stat unit. When I turn off the signal stalk back to center, the indicator lamp continues to flash about 6 or 7 times, and each time the indicator gets dimmer and dimmer, and then it stops.
DUring those 6 or 7 flashes, the lamps (both front and back) do not flash. SO in my case it's just the flasher can supplying a strange withering signal for a few cycles to the indicator. I just live with it.
Maybe it IS your flasher module...
Good luck
dave
GOod luck, I