I forgot what you said about the pattern earlier and the bowlers who run the lanes where you bowl. Intentional reverse pattern are very rare, I'm thinking it is more likely a flat pattern or a sport pattern. In an earlier post, you mention having some hold but coming in flat when you miss inside. If it were put down as a reverse block to start, you'd have no hold at all inside.
Are a lot of bowlers playing around the same area? This can happen on low ratio sport and flat patterns if there is a lot of traffic in the middle of the lane. With a lot of traffic in the middle of the lane, bowlers will start to create friction where they are playing which might explain why it starts to react more towards the middle part of the lane. Miss just a little off of that friction, it will sail into the oil where there is little traffic. Miss a little inside of that friction and you get hold, but a ball that doesn't finish. You end up with what behaves sort of like a reverse pattern to the outside, but it wasn't intentional or that way to start out. Although this is older check the response about reverse blocks that WRW Jr. gives to a question from 29/1/2002 (or January 29th, 2002.) http://www.walterray.com/answers2/lanecon.shtml
You'll find the same sort of comment about reverse blocks from other resources online, including an older post from here.http://www.bowlingcommunity.com/b/ubbthreads.php/topics/54314/CoachJim.html#Post54314
Depending on when/where the friction forms, the pattern starts to become more forgiving which can give a little more area to the higher rev players, but it won't be much. The additional hitting power might help but on sport or flat patterns the goal is to try to survive, not to necessarily throw pins all over the place.