[mr2686]

You can use a UV case, make sure it's on a OMLB, use a blue pen (bic med pt is my preference) and never touch the darn things, and still you can have this problem. Some of the problem, I believe, is the fault of some of these modern baseballs (Selig and after). Not sure how the hide is being treated, but it seems to be an intermittent problem. For this reason, I have a hard time investing any further in signed baseballs. I will get a few more to fill up the remaining spots in my cases, but I'll probably rely on older baseballs to get that done.
The other solutions I've thought about, is taking a new ball and (using gloves) wipe them down with a terry cloth rag (something a little rough but not enough to rough up the ball). May not do anything, or may allow the ink to adhere to the ball better. Just something to try.