That spring is nowhere near stiff nor strong enough to damage that brass, let alone the fact that it would rather bend outward and down if hit by ejecting brass.
I would attribute that ding to the ejection port or brass defelector itself. I bet if you took a clearer picture, and we can already see it faintly, we'd see brass material on the leading edge of the brass defelctor. That would corroborate the ding being right inline with the mark left by the extractor on the rim and the tiny one left by the barrel extension lugs on the case neck.
And +1 to Trinimon.