Some have said they'll tell you exactly what time you went online in an "unauthorized" manner. Might shed some clues.I suspect they'll tell me the same thing they told other people who contacted them: it's a pirated copy and I'm SOL.
Just gonna hope for the best.
Speaking of that, is it possible someone else in your household played your 3ds when you weren't looking? Any brothers or sisters around? Might be time for a little interrogation session.