Alright, so teh flatmate and I have been clearing space off of our DVR by recording this season's LOST eps onto tape. In watching some fo the very first episodes again, when they meet Desmond for the first time and Jack mentions that they've been on the island for 44 days, Desmond reiterates the 44 days and looks like the number means something to him. I am thinkin' he might have "slept in" once... 44 days ago, and been late to pushing the button.
When Locke almost missed it, it sounded like it was gearing up... and we know from the whole key moving and Desmond talking about his fillings hurting that the station is powerfully magnetic. I wonder if Desmond didn't screw up and that's what pulled the plane apart.