battery light on and off

[nortonfb]

Another return of an old thread.
My 07 hb has the battery light on.
My output is 13.5-13.8 with the fan, brights, emergency flashers, radio
and defroster. The battery is 12.8V.
The battery indicator does flicker every 5-7 seconds.
Battery is new as of 1/14.
I cleaned the ground & ground on the inner fender.
Also cleaned the positive connection.
The humidity here is high and is raining & will be until Sunday.
The car was purchased 2/14 and I have no history.
The dealer did do an inspection in February.
Ideas/thoughts?
Steve