Cycling hip motion outside vs. inside

So, let's say your hips don't appear to be rocking at all at the "relative range" of cadences when riding outside, however at the same cadences on a trainer your hips are obviously rocking.

Now, does that mean you should fiddle with your seat height to get it to where you are not "rocking" on the trainer?

Or

Is the trainer an unrealistic comparison, and that "other" factors outside of the differences between road and trainer should be considered before "fiddling" with the seat height?


I have had a professional fitting, and have completed my first season of triathlons/training, though only one race, though it was a HIM.