I can think of three answers:
1) he is one of those guys who wants an online date or somehting, like he likes you likes you.
2) he is just one of those chatty people. there are people who just dont shut up, texting, chatting, etc.
3) like #2. he likes talking, and you said it was 4 in the morning. not a lot of people are real chatty then, so he needed to find somoeone who was. thats where you apparently came in.