I'm a woos when it comes to my babies. If I think something is amiss, I call the vet. I think there has only been twice in 20 yrs when it truly was nothing at all and one of those I saved for when we were there already anyway. In the other instance, the dog barfed on the way to the vet and felt better after. Better to deal with it early than wait until it is a big problem. That said, if they can get you in that quickly and it seems minor, give it a day and see if she perks up tomorrow. If you're inclined to take her temp, that might be a good way to see if there is something going on that way.