Hi Gav,
Don't know that this will add value but, I have noticed something along the same lines with my son Jake. Jake's 20 mths with TLE - left side focas. He is behind in speech and a few other areas as well... But, when he is really focused on something new his eyes will get much bigger and he lifts his eyebrows. It almost looks like his face is growing. I have noticed too that he will drag his open hand from his brow to his chin over and over when he's done. Most the time this is a smooth movement, however there are times that he will stop and rub the same area really fast for several seconds like he's scratching an itch.
Wish I could tell you what he's thinking... or if it's really an "itch" or just relief that the task is complete or we've left him alone for a bit!
Take care. Let me know if your dr ever says for sure what he thinks it is!!
Hugs to you and your family!
Lisa and Kids