[snapetom]

Did you ask them why they've switched jobs?

I've been asked that a couple of times and I guess the answers have been satisfactory enough because I've gotten an offer afterwards.

As an interviewer, I've only encountered a couple of incidents where change frequency was enough to concern us. I directly asked both about that. One, I was satisfied with the answers, and he turned out to be a great dev and stuck with us to the bitter end. The other, his answers were "meh" enough that warranted more digging. Sure enough, we discovered there were other positions that were not included in his resume. We passed on him.