I Disappear

Hi there. I'm new here. I'm a huge fan of the heavy metal band Metallica, and in one of their songs called I Disappear a line goes like this: "Then it's time I disappear...". I'm not an English native speaker, though I've been practicing/learning it for 21 years now (I'm 25), and according to my grammar knowledge, the structure should be IT'S TIME I DISAPPEARED.

James Hetfield, vocalist and guitarist of the band, is a learned man. I mean he is not a redneck who does not know how to speak. Actually many of his lyrics are rally profound and thoguht provoking and his style is really varied.

So that's my question, basically.

By the way, when you ask a question or discuss something:

1) How do you know the person is correctring/answering is a teacher or some other student?
2) Do you get corrected evry single thing you write? I'm very self demanding and I'd like to be corrected on every single mistake I make because I love English and I want to learn and perfect it as much as I could with your help.

Thanks!