So I've noticed that since yesterday Annie's meow sounds markedly different. She has always had a very high pitch, clear meow, but since yesterday it seems deeper and slightly gravely. There appear to be no other changes in her health - she eats, sleeps and drinks as usual, everything in her litter box looks normal, and there is nothing coming out of her eyes or nose. She is much more active recently since we released our new 6 month old kitten from seclusion into the main house and they run and wrestle all the time. I am mainly concerned because the kitten had a mild URI and I worry that even though they were apart that somehow Annie may have caught it. Should I be concerned or are changes in meows considered normal?