Reasons for small elevations - alcohol the night before labs, tylenol or any other OTC pain relief meds the day before labs. I would not be too concerned - it is was a serious liver problem you would also see the AST elevated. If it is a MAJOR liver problem you would see low albumin, elevated bilirubin, prolonged INR. Personally, I wouldn't worry to much - but if you want more tests you could check for HBV and HCV.
Take care