There is a tax treaty between Canada and the US that recognizes RRSPs as retirement accounts. You won't be taxed on the gains in your RRSP like you would be if it was in a TFSA. So you don't really have to do anything (except fill out a form for the IRS every year).
The problem that usually arises is if you want to buy something else. I don't know of any Canadian brokerage that will sell products to a US resident. It's a question of where they're licensed. However the SEC has issued an exemption so you can try to argue with your broker to get a trade done. Link to SEC order
With such a small amount in the account you may be paying fees or have it invested in funds with higher fees. You will have to do the math on whether or not you should just withdraw the money and invest in cheaper funds and accounts in the US.
When you withdraw the money Canada will withhold a flat rate of 25% or in some circumstances 15%.
For more info go to Serbinski (a cross border tax specialist).