No, just an understanding of the Constitution. If s state cannot join without permission and once in cannot combine with another state without permission or split without permission or change its borders by a fraction of an inch without permission, then it's not hard to conclude that it needs permission to leave as well.
"Among the enumerated powers, we do not find that of establishing a bank or creating a corporation. But there is no phrase in the instrument which, like the articles of confederation, excludes incidental or implied powers; and which requires that everything granted shall be expressly and minutely described. Even the 10th amendment, which was framed for the purpose of quieting the excessive jealousies which had been excited, omits the word 'expressly,' and declares only, that the powers 'not delegated to the United States, nor prohibited to the states, are reserved to the states or to the people;' thus leaving the question, whether the particular power which may become the subject of contest, has been delegated to the one government, or prohibited to the other, to depend on a fair construction of the whole instrument. The men who drew and adopted this amendment had experienced the embarrassments resulting from the insertion of this word in the articles of confederation, and probably omitted it, to avoid those embarrassments. A constitution, to contain an accurate detail of all the subdivisions of which its great powers will admit, and of all the means by which they may be carried into execution, would partake of the prolixity of a legal code, and could scarcely be embraced by the human mind. It would, probably, never be understood by the public. Its nature, therefore, requires, that only its great outlines should be marked, its important objects designated, and the minor ingredients which compose those objects, be deduced from the nature of the objects themselves. That this idea was entertained by the framers of the American constitution, is not only to be inferred from the nature of the instrument, but from the language. Why else were some of the limitations, found in the 9th section of the 1st article, introduced? It is also, in some degree, warranted, by their having omitted to use any restrictive term which might prevent its receiving a fair and just interpretation. In considering this question, then, we must never forget that it is a constitution we are expounding." - Chief Justice Marshall, McCulloch v Maryland, 1819
Then why didn't those learned souls who wrote the document simply say that it is prohibited? Do you suppose that they were incapable of doing so? Or is it possible, as I believe it to be, that they specifically chose not to include it in their list of items prohibited to the states because they wanted those free and independent states who comprised the union to have a final and complete check on the government they were creating?