(SPOILER ALERT) Why doesn't Zoey (House of Night) Imprint on Stark?

I've just finished reading Hunted from the House of Night series so I'm past Untamed but I was wondering wondering why Zoey didn't Imprint on Stark when she kissed him when he died. He had blood on his mouth so it had to have gotten in her mouth and I think she even described the taste of it so why wasn't there an Imprint?