Adam certainly had to leave. Okov made no attempt to hide his strength: from the energy fluctuations rising and falling through the mountains since the dragon fell asleep, Adam could judge that the quantity of this giant dragon's energy was on par with a third-rank Mage, though the quality of that energy was far inferior to mana. Taken together, Okov was roughly a second-rank Mage. Extrapolating from that to the whole plane, the extraordinary individuals of the Dragon Plane ought to sit, as a rule, one grade below those of the Mage World.
There was no point in staying on in Okov's lair waiting to come of age. If that male dragon suddenly woke, remembered he had this one son of his, and on a whim decided to test the whelp's grasp of his inheritance, Adam would have no choice but to reveal his true body and fight him.