I think you should give yourself a pat on the back, at 4.5months to have him sleeping from a DF to 7am, you are doing super well in a BF baby.
There are a number of reasons why you have the (not) problem that you are talking about - I say not, because it's pretty normal & the "problem" is more how little real help we get with understanding the range of normal for a baby (some 20 week old BF babies still feed every 2 hours & that's still normal if you look at anthropological studies, its just Western Culture likes to clock watch & be in control)
Anyway, it's very normal for a 4+ month old to want to learn more about the world & be less intent on food & able to last longer. He will be more efficient & your body will have adapted & not feel full/empty the same way it did when they were younger. The fact he will last 4hours between feeds & sleep 8+ hours at night means he's absolutely getting enough milk in his feeds.
The reason he feeds longer & stirs at DF is more probably that your milk takes longer to feed at night (supply drops at night & if he hasn't fed from 5.30pm to the DF then he'd definitely be hungry (even if you feed at at 7pm before bed, it's still normal to produce less milk at night. There is also the comfort side (a good thing) the quite connection with no distractions, are good for bonding & babies are very good at meeting their basic emotional needs (& they are important needs)
In all honesty, yes he may be feeding longer at night than day, but it's not necessarily about the food, but about the big picture of bonding. So all I can say is enjoy it (esp the lack of night feeds), rather than worry about the "perfect routine" & try not to sweat the small stuff as there will be much bigger stuff to worry about for many years to come.
