I would like to bring this up again since people are actually talking about it now...
Couple weeks ago I brought up the same contradiction with madara's statement "I awaken these eye's shortly before my death"... Which was obviously false since nagato first showed he had the RG of madara's about 37 years ago and madara was still alive 20 years later to save obito....
Panels here...
Clearly madara was lying to kabuto... possibly to see how much he knew... SO he implied he himself, as an uchiha, awakened the RG on his own, then to test his knowledge further, asked if he did something to his body... and kabuto called his bluff and Implied he knew the "truth" of the RG... "Your a special Edo... I made you better then you were in your prime (EMS)... i made you complete (EMS+Hashirama=reuniting the sage's powers)"
Madara did not understand how he knew any of this or the secret to his body without reading the sage's tablet... But kabuto explained him and Oro had a hypothesis and Edo madara proved it correct... which is that by altering madara's body and adding hashirama's cells he brought the two bloodlines of the sage back together... thus his power of the RG was reborn in madara...
I think it was just madara testing kabuto and nothing more... it was taken to litteral IMO...