Intermittant Check Charging System Light

I have an 08 MDX and the check charging system light will randomly flash on then back off while presenting no other symptoms. I have an almost new battery that checks fine and the alternator was rebuilt almost a year ago. I have also replaced the hands free unit. Sometimes it will go a week or two without doing it then sometimes will do it three times in a two hour period. I have a long road trip coming up and would hate for something to happen during the trip. I have seen many threads where many lights come on and people have needed batteries and/or alternators but this is just the random flash of the check charging system. Any idea?