Waving? 👋

I "liked" someone on a dating app then they "liked" me too. Ok, cool. What was his first and only message? He waved. 👋 I've never tried to build a conversation on a wave. Is that normal? How would you respond? Not trying to be unkind but also not sure if a wave is an opening line or just a shrug. Thoughts? 🤷‍♀️