No. Actually if anything I feel like it's good luck, because the chances of something happening on two different 9/11's are so slim (though I understand that probability doesn't actually work that way; the chances are the same as any other day), except that Osama dig pick 9/11 for a reason, it's the number to emergency services, 9-1-1 (just goes to show that "all attack is a call for help"), so maybe he'd do it again. But still, how many planes were hijacked, like 3 or 4? Given how many planes were in the sky at the time, probably even still flying was more safe than driving on that day, knowing how ridiculously dangerous driving is.