Front Seat Recliner problems of the 1997 BMW Z3

Both driver and passenger seats move and shift out of place during normal operation at any speed all of the time. Reported to dealer for correction under warranty and was advised this was a normal condition for the seat to move when applying brakes at any speed. I consider this a safety hazard because the seat movement could result in deficient application of brake pressure on the pedal during braking conditions. Please advise if this is considered by NHTSA as normal operating condition.