Without knowing exactly what this guy was doing with his toy gun, I won't comment. Was the muzzle pointed up, or at something?
If the gun was carried in a possibly dangerous fashion I certaintly would have gotten very nervous.
OTOH, I have OC'd long arms before around the marina, going from one boat to another.
The behavior was certaintly suspicious enough to warrant a second look from what you describe though.
You carry a CZ-52? Sweet. I want one of those or a Tokarev. Do you have a decent defensive load for it? The military loads strike me as too fast, and overpenetrating.