3 seeds? no big deal.. it will happen.
same reason "fem" seeds are possible is how it happend... your plant grew a nanner and it knocked itself up.. sinner! lol
The seed will be XX for sure, assuming no contamination from outside, which is unlikely it seems. The problem is it is a plant that hermied on its own. Fem seeds come from a process of purposefully stressing the plant to grow male bits -- not quite the same. your plant has a slight tendency to herm or you had a light leak etc... if you think it was a little stressed, then maybe it's an okay seed? but there's a risk you simply have a genetically-prone hermie seed.
GG4 comes from a plant that hermed on accident, so ... it's not written in stone, obviously.