Most probably the boat has been blocked improperly and the stresses from the improperly placed jackstands and *location of blocks under the keel* are causing the warpage of the hull.
Especially if the far aft trailing section of the keel is sitting on a 'block', the keel aft section will tend to 'rotate up' and the flat hull sections adjacent to the keel root will 'buckle'. When blocking such keels the aft block should be placed DIRECTLY under (and slightly in front of) a line
running straight down from the intersection of the aft section of the keel and the hull; if the keel is blocked aft of the above location then the keel will apparently 'rotate' and hull buckling will almost certainly develop. Many boats of this era are subject to this 'blocking / jackstand' anomaly, and if properly 'reblocked' will rapidly resume their proper 'shape'. Such boats also benefit if the far front and far aft jackstands be set up a bit 'tighter' than those set amidships.
Pearsons, ODays and other similar boat designs will do this buckling if blocked improperly .... Nothing to worry about if not left too long and the FRG doesnt begin to 'creep' (permanent viscoelastic distortion).
Suggest that the hull be 'reset' properly on the jackstands so you can make a better decision.