I wouldn't sweat it. I went to school in WV (hold the jokes, please), where there are some pretty steep hills in the Appalachians, and all Auto tranny cars will roll back on those big inclines. The AT is a hydraulic device which uses the hydraulic pressure to engage clutch packs to transfer torque. Since you were just coasting, there was not much pressure, and the clutches could not engage. If they engaged, it was oviously only very slight, as you continued to roll back, and not skid. The worst thing you could have done was to warm up the clutches a bit. If you are really paranoid, flush the tranny with fresh fluid earlier than the recommended maintainence interval.
By the way, even in WV, the steepest on-road incline I ever saw was only 17 degrees (30%). It's amazing that 17 degrees appears as steep as it does. It seemed like it must be 45 degrees. 45 degree inclines are climbable by hard-core off-road & military vehicles only.
Cheers,
Jeffro
By the way, even in WV, the steepest on-road incline I ever saw was only 17 degrees (30%). It's amazing that 17 degrees appears as steep as it does. It seemed like it must be 45 degrees. 45 degree inclines are climbable by hard-core off-road & military vehicles only.
Cheers,
Jeffro