Embroidery thread is your friend! I've accidentally snipped a top when quilting. I use the same color embroidery thread (or a contrast if it fits) to whip stitch the small cut together then cover with a heart in satin stitch. Works beautifully and launders well.
I call it a bit of hidden love! Folks are tickled when they find them. Little do they know, that heart is hiding an oopsie!