Odd vibrate bug


My Desire (Orange Uk) decided to stop vibrating the other day. Nothing could make it vibrate - I tried emailing it, changing the profile to vibrate-only, locking the phone and moving my finger over the little circles to unlock (the phone usually vibrates a little as you pass over each one), phoning voicemail (the phone vibrates as a call is answered) and powering off and on. Then, suddenly, about 15 mins after I powered on it started working again. Has anyone else had this? Perhaps you have a quicker way of getting it working again?