Two things possible:

1.) He's old enough not to be as comfortable communicating so intimately/informallly via email.
2.) Honestly, INFps can be passive-agressive. He may be trying to send you a message he's not comfortable saying outright, in which case you're better off letting him go.

Actually, one more possibility: He might just be nervous about calling... although you did mention you two had sex (and then some), so I'm not sure what there is to be shy about at this point, lol.