We just purchased a 34RSBS and two of the slides appear to tilt inward at the top. Here's is what I found:
1. When fully extended the slide measured about 2" closer at the top than at the bottom
2. I then measured from a window ( top and bottom) frame on the slide and verified that the wall actually slopes to the inside. I believe that this is by design.
3. I placed a level on the top of the slide and found that it was in fact level.
The third slide is not built this way but, it has a different actuator to extend and retract it than the others. The first two are only attached to actuators at the bottom and, I believe, the inward slope allows the top to contact the trailer slide first. This would be to insure a good tight seal at the top when retracted. If you watch when retracting I think you will see the slide floor rise when the bottom is seating against the trailer. My third slide has cable actuators that I'm pretty sure apply pressure at the top and bottom when retracted and this doesn't necessitate an inward slope at the top.
But then again, i could way off base!!!!