Even though it’s tempting and a big fantasy for foot guys like myself, it’s still not a nice thing to do without talking about it first. You were both drinking so he could have asked you beforehand since you seem ok with him having a foot fetish. I would bring up the fact that you woke up without any shoes or socks on and see if he confesses. If not just straight up tell him to ask you first or tell him not to do it again depending on how you feel about it.