Voltage spike at power up

Last night I hooked up two leds to my Arduino UNO through 220 ohm resistors. Other than the LEDs being very dim no problem. I just need to change the resistors. But that's not what I am curious about. What is sorta bothering me is what appears to be a voltage surge when I plug in my computer through the USB, the LEDs flash very bright then off. That makes me wonder what kind of voltage is being applied to the pins. I know its supposed to be around 5V (3.3 - 5 I beleive the manual says).

So my question is this, what could be causing this surge? My concern is, when I finely get everything done and I am building the permanent circuit with the proper resistors for the LEDs, what will happen to the LEDs when the power is applied?

The LED positive leads are connected to pins 12 and 13 through 220 ohm resistors. The negative lead is to common (Arduino) ground.

Any ideas appreciated.