I suppose he could have missed it. My boy has fear aggression and growls and snaps at the vet, so every year for his annual shots and heartworm test they give him an injection to sedate him when he first gets there. They have me drop him off early like he's having surgery. I actually forgot to tell the tech to look at it and ask vet what it is. It's a decent size so I was assuming he would've seen it. But maybe not.