Val,
sounds like a lot of valadation for your son's learning style. What a precious moment. I would test for 'behavioral vision' immaturity anyway, if it's not too much of a difficulty.
There is nothing that says it can't be 'both.'
BTW - have you tried him on Non-Dinosaur books? Is his new reading ability 'solid?'
Sounds like you should make some friends in 'Heart Attack City' as I guess you'll be visiting there frequently! I hope he doesn't just 'decide' to start driving a car all at once as well. Or Dating!
Smiles,
grinity