Did you make a starter for the yeast? with WLP001 you will get better attenuation next time if you make a yeast starter to increase the number of yeast cells before pitching. If you use US-05 (the dry yeast equivalent) you will not need a starter.
Did you oxygenate the wort before pitching? After boiling, there is very little oxygen left in the wort, but the yeasts need O2 to reproduce, and with inadequate O2, you will get lower attenuation.
Have you checked your hydrometer in cold water? It is not unusual for hydrometers to read a few points high or low. If yours reads 1.002 in 60 degree water, then just subtract the 0.002 from every reading to correct the error.
Some extracts are more fermentable than others. You may get better results by using extract from a different Maltster. I have found that Muntons ferments well, but I'm sure there are others that I have never tried.
There are only 10 types of people in this world. Those that understand binary, and those that don't.
Reason: Added another paragraph