I have to agree with this. I know children fascinated by planes (I too live not far from the airport).I think it’s very common for kids to spot planes, my child does often, there is a local airfield with low flying planes close to H&J. I believe there is a delayed development in J but It’s very common in children to spot planes in the sky and shouldn’t be considered a cause of anything untoward.
Edited to add, I think it's lovely that he is now walking, you can see the joy on H&J faces.