4:30am is pretty close to when my DD was waking up for her first bf at M's age, even though she was a good sleeper, so I wouldn't think that's necessarily uncommon? I tried to cuddle DD until 5am and draw out the first feed until then when she was little (for my sake). This is how we ended up partially co-sleeping!

I know this is a good night for you, if you can replicate whatever you did, maybe that will help? On the other hand, perhaps this is a sign that she's getting better and eventually will do this often.