Yeah, sort of.
Marriage isn't mentioned in the Constitution. Therefore it's a matter for the States to regulate. If there weren't an overriding principle, that of discriminination.
For instance, physician assisted suicide isn't mentioned in the Constitution, and as such is a matter for the States to regulate. Since there is no overriding Constitutional consideration, it's legal according to the option of the State.
GWBs Ashcroft spent a lot of money simply on religious grounds and got slapped down by the Supreme Court. An example of how hard the Conservatives were pushing us into becoming another fundamental, extremist nation.