This does not look like gingivitis. Those upper middle incisors do appear abnormal, and the alignment of his teeth also appears abnormal. A photo of his top and bottom teeth straight on may help us give you better information. I cant tell if he has more incisors than he should, and perhaps those are retained baby teeth, or if the alignment is just such that they didn't form normally. Having said all of that, as long as he doesnt seem painful and he's able to eat normally, this is not an urgent issue. Just talk to your vet about it next time you are in for a checkup.