RRoD is so sporadic they'd have a hard time proving your console wasn't going batty when you sent it away. Mine RRoD'd ages ago, then it ran like a champ after that, for months before it finally bricked itself. Try it, and argue like fuck if they call you on it. Quoting the Sale of Goods Act, especially the "not fit for purpose" bit usually helps give you leverage in these situations, but I doubt they would bat an eyelid. Also, they have extended the warranty for RRoD repairs beyond that of the standard warranty, so it should still be covered.