Manager asked if I'm 'fully back' yet. What did you say?

Three weeks back from maternity leave. It came up in a one-on-one, friendly tone, the day after I dropped off a release call at 7 because the caregiver leaves at 7.30. I said yes. Not sure that was the right answer. How do you reply to this without sounding apologetic, or like you're signing up for late nights again?