Bongo Fury

I know there have been a few posts about the glow plug light coming on again for a moment of two after starting the engine, but I cant recall if there was a definite answer as to what causes this. Mine seems to only do it when it has not been used for a couple of days, or if the weather is particularly chilly. I charge the battery for a few hours when it happens, and this usually resolves the matter for a few weeks. Does anyone think that a new battery will solve this?, because it only happens from cold.....then it is fine.