CHRIS MATTHEWS: "Well, Michael, tax day today. That came up. You know, I was thinking of all the iconic events that are being told about today. Of course I knew it was tax day because I got them in. But of course, it's Patriots Day. It's also the Boston Marathon. And would you as an expert be thinking domestic at this point? I don't think tax day means a lot to the Arab world or Islamic world or certainly not to al Qaeda in terms of their world. It doesn't have iconic significance."