Unless you notice a lot of vibration in the steering wheel or the whole car while it's at idle(warm), I wouldn't worry about it.

If it's an auto, it's not necessarily bad to feel a little vibration in the steering wheel once you put the trans. in D, etc. but if it's really harsh or you can feel, or even see, the rest of the car vibrating than you've got at least 1 or 2 mounts that are in need of replacing.