no of course not just make sure that your dog is drinking enough if it is and it is still cold and sry then phone the vet's and ask them why but don't waste your time by going in this is nothing to worry about it has happened to my dog loads of times o.k so remember don't worry...
Your dogs nose may very well be dry if there is nothing interesting to smell. Nose moisture is often used (among other things) as a catalyst to smell. If the dog's nose is flakey or tender, then she should be scene by a vet. As for cold, your dog's nose is an extremity and as such it may feel cool to touch.
Dog's noses are normally cool to the touch, however, the nose should stay moist. Your dog could very possibly have an upper respitory infection i.e. a cold, a viruse or such. Make sure your dog is eating and drinking, it might be a wise idea to go see a vet.