No, casual or even prolonged skin touch doesn't cause spread of Leprosy
Leprosy is thought to be transmitted via droplets from the nose and mouth during close prolonged contact with affected individuals, though the exact route of transmission has yet to be proven definitively.
Not all individuals infected with M. Leprae will go on to develop leprosy, because only 5%-10% of the population is thought to be susceptible to the infection
because of immunological reasons.
And it's completely curable disease now.