Yesterday I noticed that my almost 3yo stallion (will be three in October) has something going on with his front incisor. It appears to be further back in the gum. He is eating normally (pasture boarded), and otherwise behaviour is normal. Is this normal for maybe a new (adult) tooth emerging?

i believe that young horses teeth do go through a faze at around 2-4 were they get there permenent teeth so quit possibly it could be the change in teeth

He may have a retained cap (deciduous tooth) that needs to come out. Have your vet out to have a look.