Deuces Wild Dream Card

I tried asking this on vpfree but got no responses so I thought I'd try here. I Have looked at Deuces Wild Dream Card paytables at many casinos. On all the machines I have checked, the help screen says the dream card is issued 58% of the time. The Wizard of Odds article says it is issued 59% of the time on all Deuces Wild paytables. Did Action Gaming make a change since 2010 when this article was published? Is the 58% a typo or was it used in making the EV calculations in the article and therefore makes the game returns inaccurate also? Thanks.