Bad Starter?

I have a '01 1500HD, recently when I start my truck, not always but about half the time, I hear this real high pitch squeel for just a second right as the truck starts. I'm assuming this is the starter going bad? Could anyone confirm that it's nothing more serious. If it is the starter do you see any reason to replace it now rather than just let it die on it's own (other than the fact it sounds horrible at startup)

Thanks all!!

KS

Does it sound like its zinging, like fast spin? If so, I would not worry about it, that is just the starter disengaging the shaft from flywheel and the gear on the starter is still spining fast causing that sound. I recently repaced a starter on my 94 chevy and the new starter makes that sound. If it sounds more like grinding or shorting out sound then you may have a problem. The starter maybe going out on you. Hope this helps.