all conjecture indeed, and without even a solid basis, as benz pointed out the commonly cited paper doesn`t have anything to do with it.
The suggested reaction is a micheal addition, and a bad one at that, amides (LSA) are totally non-nucleophillic. The only way this could happen in ambient conditions is if it were catalyzed by an unknown enzyme, but as benz pointed out LSH is a product of a completely different pathway.
Indeed, even the relatives of LSH, like methylergometrine, when synthesized in a laboratory are done using the corresponding amines, there are no laboratory conditions in which you can get the amide to react with the carbonyl, especially a substrate as sensitive as lysergic acid.
so there is not even a shred of truth here.. but organic chemistry is unpredictable and often breaks the rules assumed by man, perhaps it could happen at an extremely tiny equilibrium... benz in fact, has the power to lay it all to rest, by running a sample of LSA + aldehyde in HPLC... then again its possible the ionizing spray could even cause the rxn to happen too