Is it a big deal or am I overthinking it?

This is my first relationship and I've been with my boyfriend for 5 months so i am getting a relationship anxiety every now and then when something happens which I give too much meaning. So I called my boyfriend this morning, and left him a text that I am going for a run if he wanted to join me. He called an hour later but I didn't pick up cause I was running. I called right after and the line was busy. So I thought maybe its because he tried to call me again. I left there but after 2 hours I tried calling again and this time it didn't ring busy directly but after a few rings so I thought he hit the busy button or refused my call. I understand he might be busy so I'll wait for him to call me back. I just felt unease cause I don't like double calling and don't want to smother him certainly. What should I do now to relax my brain?
Is it a big deal or am I overthinking it?
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