When I saw my W in December she was not wearing her wedding rings either. I was furious and devastated, but I kept myself in check.
I know what it means to see it and know the feeling however have you considered that she is telling you the truth. Maybe she they were irritated, and maybe the grin is that of surprise instead of being evil.
All I am saying is don't read to much into it. You could set yourself up by thinking one thing when it is actually something else