I see it highly unlikely a multi-fire failure would be unnoticable when driven. I would suspect a loss of power, loss of fuel economy and should have a rougher than idle than what is normal with these cars.
Coil packs are usually pretty reliable, if the car is indeed having issues it could be anything from bad sparkplug wiring to ECU issues. Take it to a dealer who has the equipment to properly analyze the problem.

Just my Dos Centavos