Solid Tx/Rx LEDs

I've had my Arduino for a while now, but I can't remember ever seeing this happen: when I'm powering my Arduino with a wall wart (12V, 1.2 A) both the Tx and Rx LEDs say solid on, even if there is no serial communication. When there IS serial communication they'll flicker a bit. Despite this, everything works fine (I'm using an Xbee + Shield to transmit serial data).

I just wanted to check and make sure this didn't mean something unusual/unsafe was happening? I apologize if this has been answered before, I was unable to find it.

It's probably because the tx and rx leds are connected to +5v instead of usbvcc, meaning that the ft232 is powered by them when running from external power.

Perhaps mention this in the bugs & suggestions forum.

I've noticed that my tx/rx leds go solid on when bus powered from my switched off computer, which evidently holds the ft232r in reset.