Lily felt that stiffness when she hugged him but she didn't comment on it, just merely filing it away for later. Her promise to Peter might have to wait to be kept for a little while because as much as she hated to admit it, Sirius' well being mattered right in this moment with him standing in front of her.
"That's not a real answer." She told him quietly. "But - I'll accept it for now. And ask again once we find something for me to drink. I have a feeling I'm going to need it even more once I find out what's happened in the four years between what I remember last and what you do."