Goodness NO! That could have happened anywhere, including your own home! We went in August, ate all but one meal at the parks, and all came home perfectly healthy.
Also, you have to remember, those who got sick were transplant patients who are on medications to suppress their immune systems so they don't reject the organs, thereby making them more suseptible. It is unlikely a healthy person would have even been bothered by it.
Not only that, but the problem was not in the prepartation practices at WDW, but in the preparation practices at the plant where the Roma Tomatos were packaged. Unfortunately, no amount of washing was going to remove all traces of the Samenella.
Go, eat, enjoy, and for goodness sakes, don't worry about it!