I was recently offered a job as a firefighter. My background was not the best when i was a kid.?

It's nothing too serious and my last conviction was approx 12-13 years ago when i was 13 or 14 for battery. What do you think? I should have got it sealed or expunged a long time ago. What do you think? Should i seal it now or is it better to not look like you are hiding something?