The seal has broken in my sliding glass door. I assumed I had to replace the whole thing. Is it possible just to have the glass replaced? Thank you

Yes, you can have the failed seal fixed. Contact a company called Romac, mentioned in a previous post by John W. They provide the sliders, windows, etc... for the Developers. I think the problem can be fixed for free if it is still under warranty, or it will cost you around $300 if the warranty has expired. We considered having them fix our failed seal and keeping our existing slider, but opted for an upgrade since our home was built in 1996, the warranty was expired, and the existing slider is a bare bones quality unit. Our new Pella slider is like day and night compared to the old one, worth the upgrade for us since it is the door out to our birdcage/pool, which we use more than any other entry point in our home. Hope this helps.

In general yes, call home warranty, ask where the slider came from and the installer, call them about replacement glass.

Thanks again everyone for all the help. I have learned a lot on this subject with your assistance.