Mitch;

Replace "as fast as" with "in proportion to" in the 1st paragraph. Thinking it through a bit more, an early strip had too much bevel, and subsequent strips are trying to catch up. If the highest edge of the preceding strip is not touching the forms, a step will result - Ergo, too much bevel. In its simplest terms, bevels are adjusted to keep the strip against the forms.

Since you already have steps (no big deal as long as they leave enough wood after planing), carefully work back toward the forms by adjusting the bevel to accomodate, as any gross correction you attempt will be planed off and thin the panel anyway.

Spidey