Lost a chick out of the blue 😢

[Sher1015]

Hey all, I had two 10 day old chicks that my broody was raising. They were doing great - active, eating, drinking, spending lots of time under mama. They were fine this morning as I was cleaning the run, and then I looked over and found one just gone. She looked perfect, no sign of pecking or pasty butt. Just a thing, or do I need to be concerned? Will the other chick be ok as an only child? We’re headed out of town in a week, and I don’t know if it would be smart to add a new one right now. I have four big girls.