Red-claw molting question

[Arouse]

My red-clawed crab molted, and I had a nitrite spike (no change in ammonia level). Anyone else found this from molting, or do you think it's unrelated?

[Northernguy]

Is the tank well cycled?

[Arouse]

Yep, been running for more than a year. The crab's been there about a month. And it molted just after a 25% water change.
I just wondered if the decomp of the old exoskeleton might cause a spike.