iPhone 4S vibration sounds odd: Defective or just a change?

I just got an iPhone 4S, an upgrade from my iPhone 4. I'm using it and one thing I'm noticing is the vibration is weird. Not sure if it's defective or just different.

Anyway, the quick vibration when plugging into a power source sounds much quieter, to the point of almost being unnoticeable. However, when there's a long vibration for a call or an alarm, the phone makes an audible buzzing sound in addition to the vibration. For the long vibration, the vibration sounds louder but softer than my 4.

So did Apple just change the vibrator, or is something wrong with my phone? I guess my main worry is that this change in vibration could be a signal that the motor is going and I don't want to have that happen.

acorntoy said:

The At&t iPhone 4 has a different vibration motor than the iPhone 4S. The 4S should feel less harsh and should be less noisy especially when it vibrates on a solid object like a desk.

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Actually, I've found it to be much harsher and louder than my 4.

Macdude2010 said:

Common problem with the Verizon 4 and all 4S, the vibrating motor is glued onto the steel frame, in some of these, they will shake loose and rattle against the frame, only way to fix is to exchange

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Not sure if it would be worth it... And this is an AT&T model. Maybe I'm just not used to it.