Well if you used a FULL packet of yeast, your gravity may end up around 0.990 - 0.995
Don't believe the airlock, they don't always tell the truth
Check it again today and see where the gravity is. If it's at 1.04 still, then check it again tomorrow, if still at 1.04, then bottle, or rack it. If you notice it dropping, then it's still going.