Yes he did, and he was right to do so. Slavery should not ever have been a states' rights issue and I'm damn glad it no longer is.
Slavery wouldn't have been possible without the approval of the northern states at the time of the adoption of the Constitution. If the north didn't approve, that was the time to take a stand, not after you sign your name to a document.
The North was fully complicit in the practice of slavery. Even agreed to the Missouri Compromise, permitting slavery in new states.
South-knockers should get off their high horse.