just noticed when i smooth my puppy bullmastiff her ears feel quite warm is this normal or could it be a sighn of infection she doesn seem to be scratching them .

The temperature of the ears is a good indication of the general temperature of the dog. As a dog's normal body temperature is higher than ours, they should feel warm to us. If they feel cold, then the dog is cold.

I have a bullmastiff as well.  His ears are always warm to touch (almost as if he has a fever of some kind).  I think it is because of the way they sit.  My dog got quite a lot of yeast infections (due to dairy products) and the vet says that because his ears fold over they are more prone to infections as the air does not circulate around them well.  I dont think there is much to worry about.