Yes I think this is a completely normal reaction.
I'm at 4 and a half years - currently on Arimidex and although it gives me a few issues with joint pain I'm terrified of stopping at 5 years. I'm actually considering down playing the pain at my next oncologist visit so that I stay on it - along the lines of it's there but I can cope with it!
Part of me longs for the day when I no longer have to take this stuff but the other part of me remembers my oncologist saying you are 100% estrogen positive - you need to take anti hormone medication for as long as you can.
Congratulations on 10 years! That's really exciting for you.