Could be...this could also be normal behavior for some vehicles. I have a 05 crv and the family has a Nissan Frontier 08 and both of them lightly shudder on and off some while idling. This usually happens when the a/c or heat are on or the lights. It also happens if I turn the heat or a/c on in both those vehicles. So given the number of people this is happening to it could be a normal non problematic thing.Maybe the compressor turning on and off?