In the reaction: $$\ce{SiC + 2H2O <=> SiO2 + CH4}$$ The oxidation state of Si is +4 in both SiC and SiO2, while the oxidation state of carbon is -4 in both SiC and CH4 (confirmed by this).
Here (page 69, middle) it says that silicon carbide is oxidized in humid air.
So actual oxidation states of C and Si do not change, but this is considered a redox reaction? What a I missing?