Another question.... How deep were you attempting to plow? Many older plows held true to the rule where they were intended to be used at a depth of one half of the bottom width. (ie a 12" plow to be used at 6" deep, 16" plow to be used at 8" deep, ect) If used too deep, the furrow slice would almost always turn up on edge, then flop back to "green side up". The lead bottom MAY be taking less than a full width of cut. Let's say a 10" wide cut being rolled into a 14" open furrow. That would let it roll completely over. The REAR bottom, (or multiple bottoms in the case of a plow with 3 or more bottoms) wouldn't have that extra room to lay the furrow slice all the way over. It then stops partially rolled over, then falls back. I had a John Deere 3X14" model 215A plow that wouldn't turn bottoms 2 and 3 all the way to save itself if the plow was ANY deeper than 7". It would turn the front cut all the way over very consistantly no matter what depth.
Just a wild guess.....
But, I'm of the same opinion as everyone else here so far. Sure sounds like a sprung frame.
By the way, what BRAND plow? And is it a trip beam? (Or rigid beam)