Can you better describe the symptom of "hard to start?" Did it crank a long time before firing? Did it sputter while cranking but just not start for several revolutions? Did it sound labored in trying to start?
The first thing I'd check is the condition of the battery, the connections to the battery, and all the fuses in the underhood fuse/relay box. If the battery is over 3 years old it would be especially suspect. The electrical systems in newer cars are quite susceptible to brownouts and when starting the car there is a large current draw on the battery. If the system voltage is dropping much below 10.5 volts or so when trying to start the engine, the engine controls can do some unpredictable things.
-Rod