check engine light

Last Fri the check engine light came on so the first thing I did was check the gas cap. It was loose so I retightened it and went on my way expecting the lght to eventually go out. It was still on several hours and a couple of stops later so I called my dealer and explained to my service rep what was going on. He told me to give it a few days and to call him if it didn't go out by today. He said it takes a few days for the computer to reread the system. So we drove it all weekend and it finally went out this morning (Tues). With just under 145000 miles I'm wondering if I should get them to put it on the scanner anyway. It's$130 to do the scan so it's a bit of a ding in the budget. Do the hybrid batts need to be checked,indicator light or not? Here in Ca I think they have a 150000 mi warrenty? Any advice would be appreciated.