it could also be the blinker socket that's going bad... i had to have my left signal blinker socket & bulb replaced several years ago, because it kept burning out bulbs. turns out, the socket contact point melted and was also melting those on the bulbs. i think the socket was $15 at the dealer. (i bought an extra one just in case of future burn outs, as this car eats sockets & bulbs for lunch.)
pop the hood & locate the hole just above the blinker housing, insert a large flat head screw driver into hole (flat side parallel to the bumper) & push down to release the blinker housing clip (it pops right out), unscrew the socket, remove the socket (plastic clip releases), put in the new one & a new bulb, and then put everything back.