Can a cop pull you over because they run your licence and it says you have a warrant?

Yes, if the physical description of the subject of the warrant is similar to the individual driving the vehicle.

Another View: The physical appearance (as stated above) is not a requirement. Warrants are seldom issued with the physical appearance of the wanted subject included within them. If the warrant information indicates the registered owner of the vehicle is the one who is wanted, it is sufficient enough to pull the vehicle over. The registered owner is always presumed to be the operator. It is within the duties of the police to confirm this information and if the driver is not the registered owner (and the subject of the warrant) the mininimal intrusiveness of the stop for investigation is permissiible.