hi dave,
i have also seen a decrease in aby "staining" intensity when left in a 60
degree oven for more than 1 hour (on many different aby's...for this reason,
i NEVER leave them in longer that that).
however, i've not encountered a decrease in intensity vs. longer/cooler
heating.  but then i've not used a 37 oven either.  the only comparison i've
made is a weekend/room temp. vs 1hr/60 degree.  i was unable to tell the two
apart (we also use the 1D5 clone).
i'm assuming that your 60 oven is maintaining a very stable temp.
interesting......
carrie kyle-byrne
eire@teleport.com