Well, I just hit 56, by finishing a round at Oakmont using the Callaway Tour i(s) ball, and when I finished, it informed me that I had leveled up, and by leveling up, I had unlocked... the Callaway Tour i(s) ball that I used on that round :p
Why would it say that? You unlocked the highest level Callaway balls 11 level ago!
I know... I just hit 57 and unlocked the Callaway i(z) ball too, that I unlocked over 10 levels ago too. I just thought it funny that the game said I unlocked the ball that I was playing with at the time.
It's apparently a bug/glitch in the level announcement system.