But then, Most likely will have no effect on the image forming properties. It's separation of the elements, the glue is failing and it happens in many older lenses.
You have three choices, Live with it and be happy, send it out for repair $$$$$ or do it yourself. You have an idea how the element comes out so...........
remove it, put the group in acetone to separate the elements and recement them with "crystal clear" from the local hardware. Big box or small should carry it.
People will say it can't be done without collimating it but you can and will never notice a difference. For alignment of the elements I put them back in the barrel until the glue sets,I use a very light coat of Vaseline to keep them from sticking, just enough to see. and use a glossy spray paint for the edges.