I called a local glass place. They said that 'tempered glass' would break into small pieces, but my glass broke in two Large pieces. This gave him the conclusion that my glass was designed for higher temperatures.
Do you recall more specifically what kind of glass you got? Also, what type of stove is yours?
Mine is a sealed system, power vent coal stove. This was another question the glass cutter asked.
I guess they have to order the high temperature glass because it cannot be cut in conventional ways.