I would save your being offended for something more serious. In some families birthdays are simply not big deals so unless you see them making a fuss over everyone else's birthday this may just be how they are. And even if they do make a fuss they may not make one for you because you are, technically, not yet part of the family. My MIL has never acknowledged my birthday even though it is the same month as hers so I know she knows about it. It's just not, IMHO, worth starting something over. Your FH remembered and is doing something for you and that is what REALLY counts.