Now that I compare more closely, it is about the same size as the tooth on the opposite side. It is only a little wiggly, today I tried moving it again and it didn't seem wiggly towards the outside only the inside. I haven't called the vet yet as it doesn't seem to cause him discomfort. He is two years old, and it isn't a baby tooth (he had his retained baby teeth removed already).
http://www.link.vet.ed.ac.uk/clive/c...Shared/Dog.gif
If you look at that site it is the bottom right, just above the canine tooth #305.
Maybe I could wait until he goes into teeth cleaning? So far I've done a good job brushing his teeth so I don't think he needs teeth cleaning yet, but if I have to put him out for teeth removal I might as well do the cleaning.