Oh boy, I cringe at the thought of reopening that can of worms among a certain fanbase, and so I hesitated to make this very point. But now that you did the deed, the following is one of the "additional considerations" in the committee's bracketing principles:
The committee shall attempt to avoid moving a team or a
conference out of its natural region or geographic area
an inordinate number of times and will examine the
previous three tournament brackets to determine the
number of times a team or conference has been assigned
out of its natural region.
Key word here is "attempt," since there are so many other principles that the committee has to take into account, some of which have to take precedence. But yeah, I suspect that the committee is loath to ship Notre Dame out to Portland just one year after they were sent to Spokane.