My church assembles apple pies for sale on a Monday. Crusts are made ahead and frozen. Crumbs are made on Friday and refrigerated. This year the crumbs have become lump, hard, and almost impossible to sprinkle on the pie at assembly time. What can we do to prevent this? We don't have enough workers to make the crumbs during the pie assembly.
Obviously I don't know your exact worker situation, but it seems like 5 minutes in advance for 1 person with a food processor should be enough to make more than enough 'crumbs'? This of course depends on your recipe for your crumbs, but if it's just rubbed butter and flour with salt, flavourings etc, it's possible to 'cheat' very effectively with a food processor.
In terms of chemistry, I'd guess your crumbs got too warm before they were cooled, so the fats in them had started to bond, and lumped together.