I remember he once said something along the lines of "Life would have been so much easier if I just had a drinking problem"
I didn't get the impression he had a drinking problem of any sort and was interested to hear what were the basis of your claim.
To me he didn't look hungover, he looked extremely exausted and tired which is normal for someone who has been touring for months, night after night. I assume I could be wrong but it would take more then "he looked hungover" to convince me