Shrimp With A Line Down Its Back

My big yellow (so names because it's bigger than the others and yellow!) has a lightish coloured line down its back.
When I  first saw it I thought it was a failed moult and fully expected to see it's dead body next day.

However, it is still alive and feeding two days later, still with the lighter coloured line down its back.

None of the other shrimp have a line like this.

Is this normal for some shrimp. Please say yes so that I can stop worrying about it!!

It wasn't designated as a yellow Sue.  These were my original shrimp that I collected from a young woman who was thinning out her tank.

She was selling them as Red cherry but this one is definitely a different colour so I think she must have had them mixed in the tank.