Robob,
I also have seen this on several new records. It did line up with the inner sleeve glue joints, so I am sure it is from the sleeve. It has had no noticeable sound effect on my albums. I am also pretty sure that it not glue residue itself that has leaked out of the seams. I think it is probably a solvent that is a component of the glue that continues to offgas long after the glue has "dried" that has a visible effect on the vinyl. Maybe it could affect the durability of the vinyl in this location, but so far, I have not noticed any degradation in the sound of mine.
I also have seen this on several new records. It did line up with the inner sleeve glue joints, so I am sure it is from the sleeve. It has had no noticeable sound effect on my albums. I am also pretty sure that it not glue residue itself that has leaked out of the seams. I think it is probably a solvent that is a component of the glue that continues to offgas long after the glue has "dried" that has a visible effect on the vinyl. Maybe it could affect the durability of the vinyl in this location, but so far, I have not noticed any degradation in the sound of mine.