A lot of cold break mush can be a symptom of highly bicarbonate water that's not treated. Creating poor mash pH, causing starch not to gelatinize by the alpha enzymes. If you had a good boil and the mash and wort pH was in the park and the wort was cooled pretty quick. It is a condition caused by a brewing problem. Stirring mash to death and running off the starch, stirred into solution, through a poor filter bed or no filter bed, low boil, a poor hot break, slow wort cooling. Rack the wort off the mush, before it goes into the fermenter. The mush gives beer bitter, astringincy, some confuse with hop bitterness. Less noticeable in beer with a lot of black. In a light beer, you should rack the beer off the stuff.