2.4 inch LCD touch screen question.

Hi, I have this http://www.ebay.com/itm/131833515695?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT TFT LCD shield for the Uno. I decided to wire it to a Nano, I duplicated the pin mapping from the Uno to the Nano. It works fine. But what puzzles me is that, for the LCD, I did not need to wire either the 3.3V or the 5V from the Nano to the LCD and it still works as long as I wired the GND to the LCD. Why is that? Looks like the LCD is getting enough power from one or more of the analog pins, am I correct?