One of my hives has some cappings on honey that I have never seen before - they are very white and thick - almost looks like cotton. The involved super had some brood in it so I put on a queen excluder and waited for the brood to emerge. Now the bees have back filled those cells with honey capped with these odd caps. I first thought it was some kind of mold, but scratching it reveals normal appearing honey below. Is this normal or signs of a problem?