Cocker 3 years old

Question
I GOT A COCKER 1 1/2 MONTHS AGO (3 YRS OLD) AND GOT HIM CHECKED
OUT BY THE VET.  THEY SAID HE HAD WORMS SO I GOT THAT TAKEN CARE
OF.  NOW I NOTICED WHEN HE IS EXCITED AND RUNNING HARD WITH MY
OTHER DOG, HIS TONGUE TURNS A LITTLE BLUE, THEN GOES AWAY.  IT
DOESN'T HAPPEN ALL THE TIME. DO I NEED TO BE CONCERNED?  THE VET DID
SAY HE HAD A LOW WHITE BLOOD COUNT BUT THAT WAS DO TO THE WORMS.  
THANK YOU AND GOD BLESS!
OH, HE IS A HAPPY DOG AND EATS AND POOPS NORMAL AND HAS A LOT OF
ENERGY TOO :)

Answer
You're quite observant and an excellent owner to have noticed this blue tongue!  And yes, I would ask the veterinarian about this.  It might be the natural result of blood pressure increase after high activity, but this is something I don't know.  Ask the vet.