My iPhone vibrates for no reason!

Hi there,

I own a 16 gigabyte iPhone 4 and it is experiencing glitches!

The glitch I am refereing to is that my iPhone will vibrate for no apperent reason. One time about a week or so ago I had just powered

on my iPhone and it vibrated when it was on. My phone wasnt on vibrate nor were there any incoming messages. Today I was playing a game on

my phone and it again vibrated for no reason, I do admit I did get an email but its also supposed to make a noise when it does but

this time it didnt! My phone wasnt on vibrate for that time either!

Please let me know if anyone out there has had the same problem and any suggestions.

Thanks,

The Apple Freak