Forgot to report nontaxable 401k distribution on taxes - should I amend?

I just completed and filed my taxes for 2009, only to receive a 1099-R in the mail for my 401k distribution. I completely forgot about it and was not anticipating it. Since it was a direct rollover into an IRA, it's not taxable and will not affect what I owe or get back from the government. Should I amend my return to report it, or can I let it go? (Serious answers only please from those who have tax expertise or have faced a similar situation.)