I don't think it was meant to be a secret. We had been talking and she was becoming pretty affectionate.
I think the plan was this:
  • Find a reason to get me to come to her room
  • Call me, express reason
  • Get me onto her bed
  • Encourage me to get comfortable
  • Gently pressure me into sex, possibly more than once
  • Send me back to my room, fatigued but satisfied

If she were planning it, I unintentionally shut her down after the second list item.