I don’t believe it is a sin, but it shows a lack of trust that God is in control. It can be hard to let go and truly hand Him the reigns. We have a magnet on our refrigerator that has a nice saying on it” “Don’t worry about tomorrow - od is already there.” It helps to bring things back into focus for me.
How can God be in control when man has free will? God doesn’t control what evil people might do to you or your family.
Had did that get past spell check?
Not believing/trusting God is a sin. It’s the root of the sin of people that reject God. “It can’t be that easy.” “How can one guy on a cross help me?” “How do you not have to earn salvation, at least partly?”
But I don’t think being concerned about things and making plans to deal with those concerns is sin, unless you are so worried you are forgetting to remember God is in control and you can let go of the worry at the end of the day and are able to go to sleep. And even then, at unique times of great stress it would be understandable possibly to see why someone may feel this way.