There's just a hint of what could almost be a laugh before Castiel responds. It's not that he remembers that time fondly. It's quite the opposite. He'd been drowning in guilt and worry. Meg's presence and Dean's forgiveness had been the only things that had been good about any of it, but the little things he'd found there had helped him to understand some things that he hadn't understood before.

"I didn't keep count, but I have a feeling Meg might have. At some point, I think I was just trying to keep her attention by making her replace light bulbs." He doesn't notice that Dean's unhappy about any of this. As far as he can tell, it's just Dean not getting along with Meg, but he can't hate her that much if he left an all but defenseless Castiel with her, right?

"I can still do it if you think it would be funny, but I don't think we have unlimited light bulbs."