A friend has asked "Are you free next Sunday?" without specifying why. Now, she's done this before and I got roped into going somewhere I really didn't want to because she didn't say what it was until I replied that I was free. As it happens, I am busy next Sunday and told her so but still asked "Why?" That was two days ago and she never responded.
AIBU to expect someone to tell you in their first message why they're asking?