Phew, I was worried then until I read your last post!
A few thoughts:
You say he does seem genuinely hungry - he is still only young and it might be that he does need that feed. Has this started recently or has he always been waking for another night feed?
He's on a lot of solids for such a young baby - although this may be a rather personal view on my part, as where I come from (UK) most people don't start until nearer 6 months. However, you might want to be careful that he's still filling up on milk rather than solids - a tummy full of milk has a lot more calories than a tummy full of veg or fruit...
Also you said you were in the UK last week - where are you now, and what is the time difference? It can take a long time to adjust after time zone changes.
Finally, his last A time is really long - 2 - 2.5hrs A time is a loooong time after only a 30 mins nap. My LO is 9 months old and I would put her to bed 1.5hrs after a 30 min catnap. So it may also be that he is overtired which can lead to wake-ups... what time does he wake up in the morning (other than 4am?
)
hope that gives you a few thoughts to be going on with
Bryony