My check engine light wason in my 2005 chevy astro van.had the problem fixed.a few days later i noticed i was?

due for an inspection.the safety part ped but i failed emissions.the tech said that after the check engine light was removed from the computer the vehicl has to be driven about70 miles to"reset".because it "wasnt ready".i no NOTHING about cars.is thes correct about the driving?