Are yall sure it should glow red? I don't think so. You might want to check on that some more, my 1990 did that 1 time, I just got through running the dog sh!t out of it, and it was the only time I seen it doing that (it was at night time). They're not made to get that kind of heat, I would contact Mazda and ask them.
Let us know what you find out?
You may be running it too hard man.