心配してたんだ

I was worried about

→ 心配
phrase Uncommon #19,305
I was worried about A casual, explanatory form of 心配していたんだ. The subject and the person or thing being worried about are understood from context.
JA: 君のことをずっと心配してたんだ。
EN: I was worried about you the whole time.

心配してたんだよ

I was worried about you.

— 天空の城ラピュタ (1986)

ずっと心配してたんだぜ

I've been worried about you this whole time.

— レザボア・ドッグス (1992)

さっきまでひょっとすると天使じゃないかって心配してたんだ

Until just now, I was worried you might actually be an angel.

— 天空の城ラピュタ (1986)

トムは何か悪いことが起こるんじゃないかと心配してたんだ。

Tom was worried that something bad might happen.

トムはメアリーを心配してたんだ。

Tom was worried about Mary.

心配してたんだぞ

I was worried about you, you know.

— AKIRA (1988)

心配してたんだ

I was worried about you.

— グエムル -漢江の怪物- (2006)