Is it possible that you ate something that could have colored them red?
I'll apologize in advance for TMI... One time after eating dinner and then running for the bathroom, I totally freaked out because I had the runs and it was completely red. I thought I was dying or something. Then I asked my dad (who takes met for diabetes) and he said, "Jennifer if met is making food go right through you, AND you have dinner that consists mainly of tomato sauce, what do you think is going to happen? You're not dying!" I had to laugh when I realized he was probably right. And it hasn't happened since.
So maybe you've just eaten something that stained the gluc xr casing?
jen