It's entirely normal for interest on savings accounts to be above RPI/CPI inflation. Whether "inflation" is the proper term for those price changes is an uninteresting argument, but it's very ordinary for the basket-of-goods purchasing power of your savings in ten years time to be more than it is now (my (UK) savings account does that, and it's by no means unusual in this regard).
My savings account currently runs about 2% above inflation.