That is the weight attached to the bottom of the clubhead. Specs recommend plus 2 gram weight over standard. Not uncommon.

Like Barry said, not uncommon. The GT1 head is lighter which helps speed up the swing for slow swingers but the downside can be a lack of feel of the clubhead. Some people (including me) use heavier weights in the head to increase feel in the swing. I can better square up a heavier head. Trick is not to go so heavy that it slows your swing speed. That’s what your fitter has done, sign that you got a good fitter as some spend all the time on head and shaft combinations and not so much the weight variations. Enjoy the new driver!