Spots on boxers Fur

Question
I have a 2 year old fawn boxer.  She seems to have acquired two spots (they look like odd circles, almost like water stains on dryclean only material) On either side of her back.  The fur is just discolored. No Redness, No Irritation, No Fur Loss, No Sign of Itchiness.  She does not appear to be bothered by them, nor do they seem contagious.  We also have a male Brindle who spends quite a bit of time with her and he is showing no signs.  I thought at first they were welts or hives, but are not raised at all.  They have been there for about 2-3 weeks.  Can someone advise me as to what this could be?

Answer
Given the location, this may be related to Seasonal Flank Alopecia, which is not uncommon in Boxers (and not a health-related issues, fortunately).  Alopecia usually includes hair loss, so this may be something different, but it may just be in the early stages.  Here are a couple of articles about alopecia and some other possibilities:

http://www.dermvet.com/caninesfalopecia.htm
http://www.community.skylos.com/content/view/274/