I wasnt aware of a level cap either. I know your abilities basically cap at 100 even though the number will rise, the benefits you receive from said stat dont. I imagine its the same with your level and this is what you speak of?
I have played 3 different characters but I never went over level 45 with any of them. I basically got sick of playing the game because I literally tried to go, see, and do everything. I completed Shivering Isles in under 3 hours and didnt do anything extra there. Im not sure how high I would have been if I continued to play normally, but I just dont have another 50 hours to sink into the game.