Is my knock sensor working?

[photo@intrex.net (Bill Collins)]

On my '90 Cabriolet (Digifant) I hear it knock once or twice if I give it a lot of throttle at low RPM. (Usually when I let out the clutch in 1st gear with the engine near idle, then punch it)

Is this normal?  At first I thought it just took the sensor a few knocks to adjust the timing, then I wondered if the knocking was just going away because the engine was at a higher RPM and was less likely to knock.

Bill