1998 Honda Accord HEAD GASKET

Engine Mechanical problem
1998 Honda Accord 6 cyl Front Wheel Drive Automatic

PER THE RECOMMENDAION OF MECHANIC, REPLACED THE
TIMING BELT & WATER PUMP. CAR WOULD NOT START
A COUPLE OF DAYS LATER, AND THEY SAY THE HEAD GASKET IS BAD & COOLANT IN (2) CYLINDERS.

QUESTION: SHOULD THEY HAVE FOUND THIS WHEN REPLACING THE TIMING BEL &WATER PUMP