Buck Arrest Shock

so, I got hired in a university and i filled out the paperwork, of course i've never done anything wrong in my life, anything criminal. I only had a speeding ticket once and that's about it. I start working and then 10 days later, the H.R department pulls me to an office and says that something came up in my backround check and can't tell me and that im fired. i was in shock! i call the backround check company and they said that there was a warrant for an arrest for a bad check of $70 dollars from Dec, 2008? i guess around christmas i had too much shopping and one check bounced, i was never aware of it at all. until 3 years later... so I lost my job and now i have to find out in court of what to do? is this going to stay in my record for ever or what? why would someone would do something like that for 70 bucks when i never had the intention of anything bad.