I am so so confused. my bilirubin was 1.3 which was a bit high. doc said it was due to dehydration? was that a wrong reason why it is high?

Yes: Dehydration by itself doesn't raise bilirubin. You may have been dehydrated at the same time & this is what your physician meant. I suggest you get some rest and stop worrying about this. If this is your only elevated liver chemistry and you feel well, you may have Gilbert's non-disease or you might just have missed a meal or two. It's not danger to you whatsoever.