Hi Tina,
The surgeons always make the 'flap' larger than what the actual tongue was.
This is because the flap shrinks quite considerably when you start radiotherapy, and returns to a 'normal' size.
Hence, I am assuming that it is not the actual swelling (as you would notice pain if that was the case) but intentionally cut large having factored in Radiotherapy.
Jen had the same issue before treatment started, and the size of the tongue & flap is now on par with a normal tongue.
Hope that helps.
Jay