2007 Prius Warning Light

My new 2007 Prius just started showing me the above warning light. The manual tells me squat about it other than what it is - not what it means or what to do. The hybrid battery was low but the fob was in my pocket as usual. After a few minutes of driving, the light went out.

Was this a function of the low hybrid battery or is there another issue that I need to be concerned about?

 

Thanks. I ended up figuring it out myself today. I had the car parked and running and opened the driver's door; went around to the passenger door; opened that and removed my case and put it a couple of feet away; closed the passenger's door and got back in and guess whay? Idiot light was on. Then the idiot's light went on!