I just noticed this today, but is the townhall max level also dependent on the other building levels that you have?
Why I'm asking is that today when I levelled, I was informed that Townhall is able to go from 13->14. However, when I clicked on the Townhall, no upgrade available. It was only until all the buildings I currently have built have reached max available level that my Townhall is open for levelling again.
If this is the case, I would suggest to change it, because, it severe limits players who decide that they have built the wrong building and want to make changes later.
If its a bug, I'll just report it later if no one is having the same problem.