B.M.
Hey Stephy,
I looked up your problem and apparently this is a common thing and it may not be freezer burn. Your milk can change in taste and smell once it has been frozen. It has something to do with the way the fat breaks down and the amount of lipase in your milk, but the "experts" seem to think it should be fine.
Check out: http://parenting.ivillage.com/newborn/nbreastfeed/0,,3x9k...
and here: http://www.breastfeeding.com/helpme/helpme_asklc_ans135.html
Hope this helps.