There is often some play where the chainring tabs attach to the crank spider. Slightly loosen the chainring bolts, find the tight spot, squeeze the chain together or hit the c-ring with a block of wood and a hammer, towards the rear hub. Check it. Repeat as necessary. Retighten bolts & readjust chain tension.

edit: missed your reply. In my experience the tabs on Salsa rings are a pretty tight fit. You could lightly file the tabs so that you have some adjustment for concentricity.