It is odd for sure. Ground profile is related spring adjustment so you wouldn't think that angle would play into air movement with the fluid but it can and does at times. It's seems to be with a big Rubber Rake I find it showing up. Even with that 3" is about all the difference we are talking about. It seems hardly possible that little step could cause a problem, but it can. Odd as it is it don't cause an issue on all those jobs all the time. I have no idea what brings on these things. Probably why it is such a problem when it shows up. Really glad you got it sorted out, now you gotta retrain that right foot.