Q: Is 1,000 dollars a normal rental increase? A: No! Not normal.
My thought is that perhaps there is a new owner who believes the rent is under market value. In any event it is either a mistake or a way to get you to move.
My suggestion, if you want to stay in your unit, contact the management company and ask them a few questions, mainly the question... "Is this a mistake and you meant to write $10 per month rental increase?".
I have a feeling that you may want to look at Sean's list below and find another place to live. Sometimes Change is Good !