Items that are named by the anvil will have the name blurry or bunched up when seen in tool-tip (hovering over the object). So basically you just name the item with an anvil and hover over it after naming it and it appears blurry or bunched up. Other people have been affected by this too.
This is a minor bug but if you can fix it that would be nice 🙂.
Environment
HP Desktop, latest java version.
Duplicate of MC-23928. Should have been resolved with a ninja-update to 1.6.2. If you're still experiencing it, please provide proof at MC-23928 and ask that it be reopened.