Surely you have noticed that “changes” exist no longer. Every change has been transformed into a “sea change.” Here is the first noted use of the phrase (it has since lost its hyphen) from Shakespeare’s play The Tempest (1611):
Full fathom five thy father lies,
Of his bones are coral made:
Those are pearls that were his eyes:
Nothing of him that doth fade,
But doth suffer a sea-change
Into something rich and strange.
As you can see, that segment describes a major transformation, which is, indeed, what “sea change” means. Switching your brand of toothpaste is not a sea change, nor is taking your vacation in August rather than in June, as you have done until now.
“Sea change” has become a buzzword, particularly common in politics and advertising. Because of its frequent use, it will likely become the go-to phrase to indicate any change, no matter how trivial. You may be OK with that; I’m not. Not yet.