This is a nasty one that I've caught whilst doing the interactive animFilter tool for Red9. What you're seeing is the effect that Resample Curve has on an animation curve in Maya. Ignore the UI, I've butchered it so all you're seeing is the step value being interactively pumped into the standard resample call. Watch the graph shift in time as you increase the step. Try it yourself, I think you may be shocked at the results.
I'm doing a version of the filterCurve tool for Red9 that'll get over this issue so keep checking the Red9 blog or Facebook page for details