BB Industrial P8_18 is high and low before and during boot

Hey there!
I have a problem. I have BB Industrial, with the newest image.
I have added a GSM module, and it is powered by external 5V, as the BB doesn’t provide enough current.
Since I want to be able to power on and off the GSM module with code, i connected it to BB through NPN mosfet transistor.
the problem is that before boot, the pin that MOSFET is connected to (P8_18) is switching between high and low state during boot, which is not really good for the module.
Why does the pin float? Is it connected to the boot pins?