Is there a 31st of Feb?

Hehe..good one this...
It all started when I was chatting with a school friend and wished him for his birthday..he was surprised that I remembered his birthday after all these years.So anyways, he asked me about mine (said that he'll definitely remember to wish me)...so I said "It's on 31st Feb". It was my usual poor joke (well, not so poor anymore!) and I expected him to say -"Come on, stop kidding..tell me when is it?". Instead, what he said was - "Ok, I'll definitely wish you!" I thought, ok let's see when he realises that there's no 31st in February. No no, that's not the end of the story.
I met him online yesterday and he says - "I'm so sorry, I forgot to wish you on your birthday. It was on 31st na? I've been remembering it every morning since the 31st but just couldn't wish you!" This was unbelieveable. I thought he's pulling my leg or something. So I just played along and said - "That's ok, not a problem!" I was kinda surprised that he still didn't realise that February had only 28 days. Anyhow, I couldn't stop laughing and finally said - "Congratulations! You are the only person on the face of this earth who's experienced a 31st in February!" Poor boy - needless to say how embarrassed he is about the whole issue and I feel bad that he'll have to suffer this for the rest of my lifetime! Hehehe! I haven't laughed this much at anything in a long, long time!
Ciao,
M:)