The Geissele S3G triggers are known to double / bump fire if you do not have a solid grip on the gun. I have also had issues with the trigger not resetting while shooting prone with my SD3G trigger.
Here are some options:
1.) Always have a firm high grip on the rifle
2.) Call Geissele and tell them your issue. They have a new trigger that I have not seen in any advertisement or on this forum yet. It is called the Super V. It is made for VTAC and is a Super 3 Gun Trigger with about a half a pound heavier trigger pull. All it is is a trigger spring swap. I have played with one and it is quite crisp and feels like a fast GI trigger. I believe this will solve your trigger issues along with you changing out your BCG.

