sounds like she has some of her own stuff going on...
and sounds like she still wanted to let you know you are not forgotten... despite whatever the heck is going on with her, wether it be a cold or procrastination, etc....

um also, i really dont think you are gonna get sick from a card...
germs dont really live very long on inadimate objects.(what is it like 24 hrs or something?)
maybe you just gotta look at it from her perspective... and try to imagine what she was thinking without dismissing your importance to her.