It's so rough with old pups... Not so long ago, we had 5 Seniors (Mozart, Ozzie, Chewbie, Brahms, and Geena) all at once and we were in & out of the vet's office so often that they called us "frequent fliers"!
I hope this is just a momentary glitch for Gracie but panting is worrisome for sure. ((((hugs))))