I have heard tell of people having their warranties on RAM spuriously denied with the explicit justification that the replacement stick is "worth" 600% or whatever of what the original was and therefore the manufacturer can't afford it. So I would not at all be surprised if you learned retroactively that you can't. Of course, after already surrendering your RAM stick to the manufacturer.

I returned a memory card to Sandisk the other week, and I'm fully expecting the same result.