Nope. Martin was just a dangerously disturbed kid.
You've seen Guy Standeven in something because the man was in everything.

I think its pretty obvious that he wasn't a vampire I definitely believe he was just a messed up kid.

In the short documentary on the DVD, George Romero says he thinks Martin is a nutcase, not a real vampire.

Romero executed it in such a way that it could go either way, depending on what the audience decided. However, in my opinion, it works better thematically if Martin is not a real vampire, but rather a seriously disturbed person. After all, if Martin is really an incurable monster, Cuda was right in the end. Given how critical the film was of mysticism, it seems more fitting if Martin was psychologically troubled, more in need of therapy than ritual. However, it's ultimately up to the viewer.
They're advancing the wrong way! Retreat Backwards!

I think it was left open to interpretation. I didn't think he was a vampire, just a psychotic person from a superstitious family but you can think what you want. I like movies with ambiguous endings because they give the viewer just as important of a role in the film as the characters. You have to fill in the blanks with your own imagination.
I've been waiting for you, Ben.