Interesting... I guess it speaks volumes of the GMAC security

Sorry for the bad joke. I honestly don't think it is a big deal (someone tell me if you do - I have been wrong many times. Actually the reason I started GMAT Club is because I have done most things wrong about my prep and wanted others to avoid those mistakes). Anyway, I don't think anyone will notice really that it says "F" on your Score report rather than "M". The only information that the school checks is DOB, name, and score - that's how they match your score report in the database to your application. I mean typos and other weird things happen - I don't think it is anything that games the system really and most likely will never be noticed by the intern/student worker/admin who matches applications to the score reports in the DB. That's my take on this situation.
P.S. If you update your profile to change the gender - I don't think it will invalidate your scores and any change is electronic, so it will be reflected in the record. It will be funny if GMAC asks you to provide proof of your gender

PPS. More random thoughts and ideas - including bad ideas. You could apply as a transgender applicant and probably seriously boost your chances of getting... it is all about being a unique applicant, and this is pretty up there. This would be dishonest however, and definitely don't recommend it but since I started with a crude joke, ending with one as well.
P.S. Welcome to GMAT Club and Congrats on your score.