MarkT:
You would need a series resistor to limit the current, perhaps 220 ohms or more.However the servo signal typically has a duty cycle of 5 to 10%, so the LED won't be bright, just
flicker at 50Hz or so.
Thank you for your reply!
Yes, I will use resistors (220 ohm), the flickering is not a problem, just want to have some visual feedback to track problems easily. I was only worried it would damage the servo's or Arduino this way...