Some things are more tested (and optimized) than others. I've reported OpenGL bugs to Apple before. They actually fixed 2 of them in OS X 10.6, which I'm actually quite impressed by given that I'm hardly the most influential developer around. It didn't take more than a couple of months, also quite good. I've tried reporting bugs to other companies and had much less success, even with a lot more important bugs. If you can reproduce this in a short example, try reporting it to Apple.
I don't think your characters are stored contiguously in the file. You'll need to read them one line at a time. But I suggest you rather look at one of the many good OpenGL font tutorial, and avoid using glDrawPixels. There are faster and better ways of drawing text.