Flaky bits?

So as a quick follow-up about my experimentation with homemade laundry detergent, I did a cold wash yesterday and when I pulled it from the dryer this morning I found visible little chunks of washing soda in the lint trap.  Just a couple, but I will watch closely as I fold.  Maybe I need to grind the stuff up more, or maybe I need warmer water, or maybe it won't be a big deal either way.