This is Turtle.
I had my roof reroofed about 1 year ago with the Atlas 35 year shingles and filed on a problem with them and they sent me a check in the mail of $3,500.00 buying back the roofing job but cancelled my warranty. The problem was a rust marks showing up where the water run off the roof on the concrete and did make a bad rust stain there. The problem has been corrected now but back about a year or 2 ago it was a problem.
Just some info word.
TURTLE