I was also worried sick about all of the cards since I was out of town for a while and couldn't pick them up. Turns out some of them are yet to come. Thanks again! I really like both the card and calendar!

does this sound natural?

I got a card from a friend in the US but it took me a while to pick it up since I was out of town. He said "Glad you got it. We were beginning to think it wasn't going to make it." This isn't the only friend I exchanged cards with, so I expected lots of cards to come my way, and I was worried sick about the cards. Some cards have arrived, others haven't.

My post is what I'm going to text him in response.