Clear bubbles with a tiny bit of color at one end are almost always immature fry. Although we cannot be certain from your description, chances are good that you are seeing a premature drop of fry. It is not the end of the world but does indeed indicate a need to let your female settle in to her environment. If all was perfect in her world, she would not be dropping premature fry.
Once your female is comfortable in her new world, she will await full term conditions before dropping any more fry. It is the simple nature of female livebearers that they will await the proper moment to drop their fry unless you encourage them not to await it in one fashion or another. I try my best not to present them with that choice since I want only the best, most mature, of their fry in my tanks.