teeth shifting years after braces?

I had braces from 15 to 17 to push a tooth forward basically on top row and straighten bottom teeth. I never wore my retainer. My teeth have been fine up until now, I'm 24. Seven years later is it possibly for my teeth to start shifting now or am I imagining things? I look at old pictures from when I was 18 and to me it looks the exact same but then I look in the mirror and obsesses thinking my tooth is shifting back.. Is it possible after these years?