What can be the cause of an elevated conjugated bilirubin with normal total bilirubin?

Not concerning. As long as your total bilirubin is normal, the proportion of direct to indirect or conjugated to unconjugated bilirubin, is of little significance. It is really only of concern, if the total bilirubin is elevated.
Bilirubin. This doesn't make sense. The total bilirubin is the combination of unconjugated and conjugated bilirubin. So, if the total bili is normal; then the conjugated has to be normal, as well. Please double check. .