That'll happen. My simple-wisdom is...it's almost impossible to ruin moss, and just when you think it's dead...IT GROWS BACK!!
I tore most of my Fissidens out of my 57gal tank and threw it away because it had so much algae in it. Apparently there were little bits of it that had taken to the wood in the tank and is now growing back in a cool "carpet" affect on the manzanita.