As I recall the warning it uses words to the effect if the student " purposfully" gives false or misleading information. You did not do so on purpose because it was only after the fact that you came to realize your parents were shading the truth a bit.
DO not worry about it--move on. If you ARE contacted by the US DOE or the US Treasury regarding discrepancies in your FAFSA, see an attorney before you respond to them. That said, it sound like you have NOTHING to worry about. Have a great life!
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