Not at all, i think there was a bug with Ditto or using the cheat "Maple" . Is one of the option can be related? Let me know on which version (number, last one is 2.0.3.5 and the normal, full or cheat version)
this is probably it hen, in 2.0.3.5 it's probably fixed (it wont decrease the stats) but unfortunately the stat will stay the same (else I would have to reset all girls stats or make a complex fix that could bring more trouble). If you have a previous save, i think it's the easiest option (or go on and raise her stats later.
Sorry about that, hopefully there won't be as many important bugs in the future, this is mainly due to the engine change and the huge amount of coding connected to it