Most likely was an extruder problem, PLA and all metal hotends tend to develope issues, even with an original e3d v6.
Several things can be done to prevent future problems:
1.- correct temperature. What temperature did you used?
2.- Extrusion rate.
3.- clean extruder gears before start printing.
4.- clean nozzle before printing and after material changes.
5.- extruder tension, chech that the gear grab firm the filament.
6.- printing speed to temperature "ratio" the faster you print the higher the temperature needs to be and vice versa.
7.- PLA cooling fan might be cooling the nozzle.
As you can see, several things might be at fault, thats why the awful and tedious task of observation it is still so important to spot a problem and understand why happened and how to prevent it.