At the blackout time, some light had entered the box from the corner of the window, and I realized it too late. Do you think I'm in trouble?

It can cause trouble, depends on how strong the genetics of the plant are. Some herm easily and a little light leak could be enough to get them to throw out a few bananas, but often it's not enough, so just keep an eye on them for anything that looks like a male flower or banana in the bud if she's further into flowering.