No, it is true. Since the curvature of the canopy actually provides a small amount of lift, the CoP was disturbed just enough, and the CoG moved sufficiently (thanks to GIB bang out) to effect a stall recovery and subsequent landing.
It was also the case on another aircraft, but I am trying to remember which! I know it was an RAF type - possibly the Hunter trainer (although not a deep stall, but an unrecoverable made recoverable by CoG and CoP movement after rapid weight loss
)