I Have a T-Mobile Touch, How to make it vibrate only once?

[xaccidentalriotx]

hey i have a t-mobile touch, and each time i put it on vibrate, it keeps vibrating until i open my message and it annoys me. Before it only vibrated once, and i dont know what i did to make it vibrate multiple times as it does now.
Please tell me what to do to fix this
thanks!