Sometimes the paypal emails don't ever turn up.  I'd rely on what's showing in your paypal account, and if it doesn't show as a CLEARED payment I wouldn't post.  With e-cheques you usually get a message saying not to post until they've notified you that they've cleared, and they usually take around a week or so.

I'd be conveniently not home this afternoon.  That gives you time to think and takes a lot of pressure off when this sort of thing happens!  If you sent an invoice early on and they know you're home, then you obviously had some sort of emergency that had to be attended to straight away.