Date arithmetic in Leopard


Apple documents this:

Look at this code:

In Tiger, the result is today’s date, in Leopard, you get a date somewhere in february 1907.
I tried figuring out where thing go wrong:

is still OK

returns a wrong date

The workaround for my problem above was to cut the number in chunks of 5.3687E+8, and add them in a loop, adding the remainder of the division after the loop.
Am I misreading Apple’s documentation ( again ) or did I stumble over a bug?