You're correct Maz.....8 is used dagnostically as the benchmark for diagnosis of diabetes here in australia.
I think he is probably fine Mel.......if he had only eaten 1.5 hours previously and the meal contained carbs then his blood sugars would have been peaking right at the time you decided to test him which explains the 7.7. Also young children have a wider range for what is acceptable than adults as they tend to swing more. for example what is considered a hypo (low blood sugar) in a newborn is lower than that for an adult and the same at the other end......7.7 1.5hours after food especially if there were carbs in it is not bad.....
But my disclaimer is if you are still worried get him checked out by a doctor.
Also as you first raised this issue a few weeks ago now I would expect that if it was type 1 developing he would be a lot further down the road to being quite noticeably unwell by now. When I was diagnosed I had gone from healthy to 7 kilos lighter in the space of a month......it is usually quite dramatic.
Again though if in doubt, ask the GP......