While I was out Saturday riding I came up to a light and as I let off of the throttle and slowed down (clutch in) the RPM's dropped very low, (bike almost dying) and the battery light started to come on. I immediately gave it some gas and the bike kept running as usual. Then I became paranoid the rest of the ride. At every stop light the idle was around 800 or so on the tack. After getting to my destination I shut her down for a few hours and then got on, cranked fine and went home (about 30 miles). Everything worked fine. Stuck her on the Battery tender and it blinked green showing 80+% charge available. Now I am paranoid as to what would of caused that to happen. Any ideas what I should check?