Failures of memory vs. failures of remembering

I was just working through an example in my paper, when I hit upon a bit of common sense: when we say (as an excuse) "My memory failed me" or "I just forgot" this often doesn't pick out a failure of memory per se but a failure in remembering.
When I forget your birthday, it's not that I'm unable to remember that today is your birthday, it's just that I didn't remember. If I literally could not remember that today is your birthday, you should probably be more concerned with my neurological health than your value to me!