Are Vaccinations Within The Gap Of Three Weeks To An Infant Advisable?

Is it safe to give our baby 4 vaccines instead of 3? The nurse has administered shots at 8 weeks, 13 weeks and 16 weeks meaning there was only 3 weeks between her second and last shots when there should have been a 4 week gap. We are now being told our baby needs to have her last set of shots again. Is this safe for our baby?