It's been 10 mos since hip replacement but hip is still feeling tight and sore when I walk or go up stairs, is this normal?

Maybe. People vary tremendously in how long it takes to heal from surgery. If you are concerned please speak to your surgeon.
Can be. I frequently see patients after hip replacement who have pain on the side of their hips. This is often diagnosed as trochanteric bursitis, and represents incomplete muscle strength recovery after surgery. If x-rays show the prostheses to be intact and stable, then soft tissues are the most common source of lingering soreness. They can be corrected with the right treatment.