it may be normal, they do tend to seek a quiet place to have their fry....but ...how are your other fish behaving? Do they seem normal? Has anyone been hassling your preggers girl? Can you test your water stats for ammonium, nitrite, nitrite? If you're not sure, a partial water change won't hurt your pregnant girl, will keep you on the safe side re: water quality, and may stimulate your girl to give birth ( 4 days early should be ok...).
Hope this helps, there is also a live bearers section further down the forum where you can get lots of good info relevant to your situation, and get advice from lots of people who have lots of experience with mollies.
