Yes, I believe you do, though it's not because it's a library, just it's functionality.
From the /playground/code/timer1 documentation;
initialize(period)
You must call this method first to use any of the other methods.
You can optionally specify the timer's period here (in microseconds), by default it is set at 1 second.
Note that this breaks analogWrite() for digital pins 9 and 10 on Arduino.
Paul