Yep I get this as well, it's the rubber bushes that are worn/split that causes it. If you turn it 90 degrees you will find the seat slides sideways when cornering instead. Mine has started to slide forward again now so the bushes have probably gone completely. I haven't seen that guide for the Civic before but I can't see the photos at work so will look at it later. I was going to get some replacement bushes or grommets to see if I could fix it.