unforunately i cant reproduce it in jsfiddle…… heres my code though regardless: http://jsfiddle.net/nZePr/
basically when you hover over a tooldtip, it leaves a very faint ghost of about 5% opacity and it doesnt fade out 100%. can you guys see anything wrong with my code? this is what it looks like:
You can see the very faint outline of it bugging out.

I found out the problem is exaggerated if you try to animate too much in a very small increment. i moved the distance that the tooltip has to travel a few more pixels and it also cleared it up. also reducing the time by .1s also helped. it has it about 1% now but its so hard to see that its all good to go 🙂