Hmm, well I have it kinda solved.
I got it to stop turning back on by disabling Keyboard/Mouse wake. But I still have no idea why the keyboard/mouse is suddenly auto-waking it when it hasn't been for the past year I've been using sleep mode.
Any idea what may have changed without my knowledge that would cause them to start doing this? (I know nothing is causing movement that may be triggering them, it does it even if I turn the mouse off, and the keyboard would be fairly obvious if it were getting hit)
Thanks again for your help.