I'm new to rafting but not to rivers. I just took delivery a new 15' SOTAR SL Elite, manufactured last week. The flat area on the top of the tubes where the frame rests has a pronounced bulge on the top center of both sides. The causes the Recretec frame which was built for this model not to fit flat on the tubes but to teeter totter back and forth ( I haven't strapped the frame down yet). My concern is all the weight of of the frame and cargo will be confined to this small fulcrum point and not distributed along the length of the frame. Is this normal or do I have a defective raft? Any advice would be appreciated.