Will a crayfish die if his gills stick out from a bad molt?

I work at a pet store and am still new. I noticed one of our electric blue crayfish has 3 feathery strings hanging from its side after a molt I read somewhere it was his gills. He is still a pinkish brown. His tank mate molted the day after him and is a much improved blue and has no issues. The water quality is 0 ammonia and nitrites, ph is 7.6 and the nitrate is down to a 5 when I started it was off the scale. I was told it was a bad molt and don't worry about it and it was my fault. So I'd like to know what you think please.