Yes, well, the problem is that many courses on "logic" don't teach model theory, at least from what I've heard. Try it and see. I could've just been asking the wrong mathematicians - e.g. a young mathematician visiting CFAR knew about model theory, but that itself seems a bit selected. But the modern courses could be better than the old courses! It's been known to happen, and I'd sure be happy to hear it.

(I'm pretty sure mathbabe has been through a course on formal logic and so has Samuel R. Buss...)