Mailed today and realized I made a small (hopefully) error

I applied for three kids, two girls, one boy. I just changed the page 1 information since it was the same. But I JUST realized, I forgot to change the gender from F to M for my son :( I reviewed and re-reviewed this form SO many times I can't believe I did this. Does anyone know-will they send my whole package back for this reason? Or-is there any way to correct this.