My husband noticed that myupper back is starting to become roundedin appearance. why is this, and will my posture continue to worsen?

Osteoporosis?: Sounds like you may be developing kyphosis (commonly called a widow's hump) which results from osteoporosis of the thoracic area of the spine (and most likely elsewhere. You should see your doc to check your calcium levels as well as schedule a bone density test (dexa scan). Dairy products, green leafy veggies, calcium supplements (citrate is absorbed best) + vit d3, and exercise help—>.

Self-correct: At your age, it is more likely a habit than destiny. You need to practice / emphasize standing up fully and not "slouching" forward, as can lose vertebral height over time. Chiropractor or physical therapist can often help if not succeeding with self-correction.