Whether it's "quite common" may vary a lot from department to department; in some places my statement may perhaps have been too strong. In the places I've seen firsthand it's quite common for tenured faculty to sometimes interview elsewhere. I did so, and made a jump.

This is also a common strategy for people angling for promotion or a big pay increase -- get an offer elsewhere, and then use that offer to get a promotion at your current institution. I'm not recommending it, but I've certainly seen it done. Common outside academia too, of course.