Ford studied Mia as she cooked breakfast, guiltily thinking over what he'd overheard in the night. He hadn't meant to eavesdrop, necessarily.
Ford had been concerned about his power after he'd regained consciousness. He felt the sharp pain of his injuries for some time thereafter, and was unable to stop it.
It turned out that magic running low was a draining experience.
But, better to learn about it now than in a situation more dire. Daniel's minimization of the creature as being weak or young was a little insulting for reasons Ford couldn't quite pin down.
Maybe it felt like his accomplishment of hiding them from it was lessened somewhat. In any case, the boy had been pleased as punch with himself over his conjuring of a giant wasp to scare off the chimera in tandem with Grandpa's swarm.
