How do you know it is 1/8 too wide? Are you comparing it your previous piece or a dimensioned print? Have you tried it in the door and found it to be too tight?
If you are comparing it to the glass removed the old glass could be undersized.
I have tried it in the door, will not go, The old glass was cracked. After trying to put it in I laid it on the old glass. 1/8 short. I talked to a glass co. It is tempered glass, he said no one could shorten it.
As the owner of a glass shop for many years, I get this question a few times a week.
Technically you can "sand"/grind tempered glass, but only to an unknown point. After that point you have a pile of glass crumbs to clean up off the floor and/or out your machinery.
For too much information see:
The compression zone of the tempered glass should not be altered.
While tempered glass has been ground down "successfully" you are left with a lite of glass that is much more unstable and subject to "spontaneous breakage".