The recently released April 2011 (Vol. 22 No. 4) issue of Robin Snyder's newsletter THE COMICS has a short letter by Steve Ditko, commenting on Reed Crandall and his work in TREASURE CHEST Vol. 16 No. 7  (available here) after Snyder ran the cover in the November 2010 issue (Vol. 21 No. 11) of the newsletter.
Information on ordering Snyder's newsletter over here.