Well, I did think it sounded strange.
I do the same as you Walter – take out the pre-installed memory and replace it with my own – in matched pairs.
It’s certainly possible that one of the sticks I was sold was “bad,” the thing of it is: The Apple Store (who are representing the warranty, lest we forget) say that any stick other than the Apple brand can’t be “guaranteed” to function with the voltage being used in these machines.
I know this is the party line, etc, but as spurious as it might sound the fact that the memory failed would lend it some creedence – especially since we’re talking about a very reputable dealer who has been mentioned on this forum many times as the first choice for RAM by a good number of folks hereabouts.
Moreover – so long as the memory we’re using isn’t Apple brand, does this mean that any problem can be reduced to, “Not the right memory”? Effectively making the warranty a bit… Well… Useless.