@jimrobb,
Thank you, Jim.
As you can see...the background hatching disguises the fact that the lines end artificially in order to allow the yellow shading to be drawn covering in a way that makes it look as though the word appears strait. It would be easier to see if the background hatching were eliminated. In a true optical illusion, the background hatching would be the cause of the effect. Here...it is just used to disguise the way the yellow shading is done.
Interesting effect nonetheless!