No, never. Sounds like maybe you don't have a lot of tandem miles yet? Or maybe you ride your single a lot more than your tandem? Tandems do steer differently. After exclusively tandeming for a long time, when I get on my single I'm all over the place, way oversteering. On the tandem, relax and when you are steering a line, don't try to correct direction quickly, like you would on a single. Instead, think of making its average advance vector equal the direction in which you want to go. Just slow it all down and don't worry about small, temporary changes in direction. After 1000 miles, you'll be able to ride it right down the fog line, completely relaxed.

You probably are feeling your stoker. Maybe she bobs a little. Make sure you are pedaling a round stroke and encourage her to follow your pedals (IP).