While I didn't see you with 〜うちに

よつば:

「しばらく見ないうちにまた大きくなった！」

"You've grown bigger since I last saw you!"

Literal: "During the time I didn't see you, you've gotten bigger!"

ジャンボ:

「お？どこでおぼえたそのセリフ」

"Oh? Where'd you pick up that line?"