I wouldn't either. Most of these things create anti-bodies and they're all set for a very long time, if not for their lifetime. According to my vet that I told I didn't want them to have anymore of most of the vaccines, he thought they likely acquire a natural immunity by the time they're this mature anyhow...probably came across a little of this and a little of that...and we don't even know it. And titering is good once in a while, but like you say...you just did it a short while ago. I don't take my dogs to too many places where there are a ton of dogs so maybe it's more of a concern for you. Or like if you have to board or take to a grooming place. I don't do either.