No region or other entity under the jurisdiction of this Constitution at the date of its original adoption shall secede from this Republic, nor shall any Region, state, or other entity declare itself outside the jurisdiction of this Constitution.
I would argue it's not secession since it's the federal government that releases those territories in the first place.
1. there is no secession
2. There is no declaration of being outside the juridisiction of this constitution since "federal government" isn't included in this text.