AppleCare+ will cover you for up to two incidents of accidental damage from handling, each subject to a service fee. I think it's $69 +tax for a Watch Sport replacement under AppleCare+ accidental damage.
"(v) The Plan does not apply to cosmetic damage to the Covered Equipment, including but not limited to scratches and dents that do not otherwise affect the functionality of the Covered Equipment."
http://www.apple.com/legal/sales-support/applecare/applecareplus/docs/applecareplusnaen.html
It would cost 65€ here in Germany. Maybe I will call Apple tomorrow. No Apple Store near me. Or I just live with it.