[BrianG]

The first write-up left out the current-limiting resistor. Leaving that out reduces the LEDs life. The only thing saving those LEDs is that the supply voltage is a little lower than their true Vf value (typically around 3.6v).

Also, you can make things a little easier by using rectangular LEDs instead, but I've only seen those type in red (which have a different voltage of around 2v if memory serves).