If it's closed like the first pic regularly, I wouldn't worry to much.... Mine does that all the time. When I did lose my first nem it looked like a drooping slime of a nem. If that happens take it out ASAP. However I have read that some nems come back from near death and major bleaching.
Hmmmm.... I'd key an eye out for if. If it starts to shrink a lot that's another bad sign.