Question on coolant level....

This is actually in regards to my 95 Z28, not my chevelle. I would have posted on LS1.com, but it takes a very long time to get a response.

Long story short....

Blew a head gasket on the car a while back, and replaced it. I've put 700 miles on the car since, and it's running quite well. Well recently my "low coolant" light came on in the car. I noticed that my resivoir was a little low, so i topped it off, but the light stayed on. The coolant level in the radiator is good, but i noticed that I filled the resivoir a little too much, so i drained some. The light still comes on. Fearing the worst I checked my oil to see if there was a bunch of anti-freeze in it, and there is basically nothing. (Just a extremely small amount after flushing it through with oil changes from before)

What do you guys think? Bad sensor? Anything to worry about? Any ideas? I'm just a little paranoid now since it had a blown head gasket before, and now the light is on.

Also, there is no white smoke out of the exhaust, so it SHOULD be ok.

Any help would be appreciated. THANKS!