ICS MP5 A4 semi-auto mode shoothing more tha one BB's
 

I recently notice that my ICS MP5 A4 shoot in a short burst action when I switch the fire selector to the semi-auto mode (2 to 3 BB's) ?? It happend more when I passed from full auto to semi-auto.

Does anyone experimented the same thing ? Is there something I can make on the first hand ?