Shelf Life of Bisquick Stored in the Refrigerator?

Since my husband and I don't finish a box of Bisquick very quickly now that the kids are gone, I wonder how long it is safe to use. I started keeping it in the refrigerator, thinking that would keep it good past the "Best by Date". The date on my box is June 12, 2010, I used it for waffles this morning and they were great. Is there a safety problem in using it past the best by date if it's been stored in the refrigerator?

Norma