If it flexes enough times, it will break. Possibly the tension was different on that one spoke relative to nearby ones, and it flexed more just while riding around.

If several spokes break in a short time frame, it's time to rebuild the wheel or get a new one. Just one spoke, it's too early to worry about.

No idea what to expect from the shop, but if you want the wheel re-tensioned I'd think it would be best to discuss it with them before they do any work. Otherwise, they might just replace one spoke, tighten it enough that the rim is true and no other diagnostics.