Ok the last 2 days i have been haveing a battery light flash on and off.

Ok it has only happened so far when i'm in fifth gear going about 60 mph at about 3000 rpm the starter and battery are only a month old and the altinator is about 9 months old . battery cables are clean and tight there are no after market things installed that would put any load on the electrical system and right now there is not even a radio in the car . I'm just looking for a few suggestions so please just give me a shout . Oh by the way my car is a 1989 civic si with the stock d16a6 and transmission.