I experienced the same problem in two areas of my Meridian. I think it is caused by slight movement of the vertical structure vs the horizontal (floor).
In both areas, I was able to access the tile piece inside a cabinet area, and pull it back to its proper place and then staple it to the sub-flooring. (On mine, one tile was under the corner of the shower, the other at the coner of a linen closet.)
The staples are out of sight, and after one summer's travel, are now out of mind.