It shouldn't be surprising. Kaworu always was odd, and wandering out in the ruins by himself where one of the few sources of happiness (Shinji tried not to think of the others the Angel had mentioned) was located.

He'll do his best to shove aside his disappointment. He shouldn't waste anymore of this guy's time.

"I'm sorry for bothering you," Shinji says. He speaks slowly, as if trying to carefully piece together his words. "If... when he comes back, tell him that... I'll drop by again tomorrow."