red tongue

I got 2 kittens to foster yesterday. They are both female. One is black and
white the other all black. I'm guessing they are around 10 - 12 wks. Their
mother was a ferile/stray? who got hit by a car late last week.

The black cat has the brightest red tongue I've ever seen - not dark pink -
red. She has also been VERY aggressive and will leap across the cage at me
when I look in at her. Is the red tongue a sign of some illness or could it
be from increased blood supply because of her agitated state. Her sister
does not have the bright red tongue but she doesn't get as agitated and will
let me pick her up and pet her.

W