I brewed my first English Brown Ale a few days ago. During the 60 minute boil I noticed that a large layer of foam developed. Which I have read is completely normal, but it left a lot of sediment looking material on the sides of the inside of my pot. I did not stir this material back in I simply left it on the walls of the pot and racked the wort away from it. What was this and should I have mixed it back into the wort as the foam subsided?