Replacement pane of stained glass for an antique door
We are in the process of re-modeling a turn-of-the-century gabled ell in Indiana. We need to replace the front door, and we bought this beauty (sorry the picture is sideways) on craigslist. It was removed from another house in the area, also about 100 years old. It is missing one pane of colored glass, about 4"x12". You can see it is on the right, second from the bottom.
I need to find and install a replacement pane of colored glass to this door so we can install the door before the weather gets any colder. When I contacted a local glass company today, they told me I had to use tempered glass since it's in a door. I told them, the door is 100 years old! I really doubt the rest of the glass is tempered. They said nevertheless, if I'm replacing 1 pane, it must be tempered.
So does the pane have to be tempered? Where can I buy 1 piece of colored glass? What type of glass should it be? Can I just buy stained glass, like for art stained glass, or does it need to be something else?