Different terms may have been used, but secession was directly discussed during the Hartford Convention of 1814-15 and during the debate over the Alien and Sedition Acts in 1798-1799, as well as when 11 states seceded from the union to establish a new union (without North Carolina and Rhode Island) in 1788, as well as in the debates over ratification of the Constitution.No one ever mentioned the "right of secession" before that time either.
Here, for example, is an objection to the Constitution from the address of the Pennsylvania anti-federalists from December 12, 1787:
"...the absolute command of Congress over the militia may be destructive of public liberty; for under the guidance of an arbitrary government, they may be made the unwilling instruments of tyranny. The militia of Pennsylvania may be marched to New England or Virginia to quell an insurrection occasioned by the most galling oppression, and aided by the standing army, they will no doubt be successful in subduing their liberty and independency. But in so doing, although the magnanimity of their minds will be extinguished, yet the meaner passions of resentment and revenge will be increased, and these in turn will be the ready and obedient instruments of despotism to enslave the others; and that with an irritated vengeance. Thus may the militia be made the instruments of crushing the last efforts of expiring liberty, of riveting the chains of despotism on their fellow-citizens, and on one another. This power can be exercised not only without violating the Constitution, but in strict conformity with it; it is calculated for this express purpose, and will doubtless be executed accordingly.”