No, she's out for some reason...

Not finding Twilight in her bed spike gingerly crawls downstairs and looks around, no Twilight there either, and there is no light in the basement, so he grabs his key from the kitchen, heads outside and locks up behind him. As far as Spike is aware, and he has read just about every book on dragons he can find since his near disastrous sojourn following the great Dragon Migration two years ago, this event is unprecedented. Sure if a dragon accumulates too much of a hoard too fast they can suddenly grow to massive size while losing almost all intellect, but he can THINK just fine and this seems to have affected his reproductive capabilities, which normally don't change under such conditions...

There are only four people he knows of who might be able to answer the question of what is going on: one, his mother Princess Twilight Sparkle, is missing, Another, Princess Mia Motori Cadenza, better known as 'Princess Cadence', lives thousands of miles north in the Crystal Empire, so she's out too: but the other two: Princes Luna and Princess Celestia are just an hour's flight away in Canterlot, and while Princess Celestia will be asleep at this time of night, Princess Luna knows more about dragons ANYWAY, and would probably be willing to talk to him about whatever the hell is going on.

However he pauses before launching himself into the air: what if this change does not last past dawn, like in one of the Flutterpony Tales that Twilight used to read him? Could he be giving up his ONE chance with rarity just for the Possibility of answers to WHY he has been gifted with the body of a 'young adult' dragon?