Can I be fired for calling off at JcPenneys for a semi-family emergency?

My Girlfriend just bought a 2011 Harley Sportster and last night she took it out for a ride and it started making a clanking noise and the oil light came on. My girlfriend has finals today so I said I'd see if I could stay home to get it taken care of. When i called in I told my supervisor that it needs to be taken care of today to prevent any kind of warranty infringements and I'm the only one who even has the option to stay home to get it taken care of. I offered to work on my days off this week to make up for the lost 4 hours of work today, and she didn't seem overly upset at the situation, but I have never called off of any of my jobs, even when I'm sick. So I don't know what the do's and don't are of calling off. Do anyone think I'll get fired for this since I've only worked there for a little over a month?