Why do he get so worried when it takes me a bit to call him back?

Anonymous
My guy friend and I talk all the time. Like all day from morning to night. Beginning with a good morning and ending with a love you good night. Our normal day ends with 4 hours of conversation on calls (doesn’t include text or In person seeing) I am a very quick answer most of the time but sometimes I don’t hear the phone ring or get busy with something. He goes back and forth with being cool about waiting for me to call back. Or texting me and messaging me and calling me again if it’s within 15 mins. Why does he go back and forth between being chill about the delay to slightly freaking out over it
Why do he get so worried when it takes me a bit to call him back?
2 Opinion