That was in a trial for ADHD treatment in adolescents. As a result, they don't advise the use of Modafinil in children. It is unclear to me whether the 933 studied were adolescents, and if so, whether or not a similar rate of rashes are seen in adults.
The Wikipedia page also says: "From the date of initial marketing, December 1998, to January 30, 2007, FDA received six cases of severe cutaneous adverse reactions associated with modafinil, including erythema multiforme (EM), Stevens–Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug rash with eosinophilia and systemic symptoms (DRESS) involving adult and pediatric patients.
I have to admit, six cases in eight years doesn't strike fear into me.
Those six cases cover somewhere upwards of 700,000 patient-years; the final estimate I found was that the risk roughly doubled from 3 SJS cases per million people to 6 cases per million people in modafinil users. (None were fatal, incidentally.)
Given that they are all different conditions, I'm guessing it's more likely to be reactions with other drugs, diet, conditions, etc. than a side effect worth worrying about.
The Wikipedia page also says: "From the date of initial marketing, December 1998, to January 30, 2007, FDA received six cases of severe cutaneous adverse reactions associated with modafinil, including erythema multiforme (EM), Stevens–Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug rash with eosinophilia and systemic symptoms (DRESS) involving adult and pediatric patients.
I have to admit, six cases in eight years doesn't strike fear into me.