I would not worry about one number - besides, with allowable meter variance (20%) it could be yellow.
It might be a random odd reading, he may still be settling, he may still be reacting to the low 100s. I would not raise the dose yet until you can get a curve. I wonder if he was a little lower between PS and the +7 today and is just not used to that yet.
Hang in there! You re doing great and it is early days yet.