How does it "re-exposed yourself to mortality risk"?

This is pretty simple. I take my payments at 62, say I get $1500 a month ($18,000/yr). At age 65, I will have collected $54,000.

Oops, I say, I want to give it all back and start over, so I go through the application process, write a check back to the government for $54,000, and stand in line for my new, improved benefit of around $2,000 ($24,000/yr).

I die the next day. My estate is $54,000 poorer. In fact, just to catch up, since I'm only getting an "extra" $500 a month, it takes quite a while to break even.

The numbers in the chart below are cumulative. By re-starting at age 65 you get a bigger payout, but it takes you to age 73 to break even. If you die at any point before age 73, you (or rather, your estate) is behind.

Year     Start at 62     Start at 65

1        $18,000
2.        36,000
3.        54,000
4.        72,000         $24,000
5.        90,000          48,000
6.       108,000          72,000
7.       126,000          96,000
8.       144,000         120,000
9.       162,000         144,000
10.      180,000         168,000
11.      198,000         192,000
12.      216,000         216,000

Of course this ignores any interest you might have gotten with the $54,000 during those first three years, but in today's climate that amount can pretty much be ignored.