I think the stats should be capped at 12 especially at the generation of a sheet.
It's feasible, otherwise, that you could start with a 13 statistics (11-2-2 and spending 10 gen to up a stat to 13) and that's too high to start at in my mind.
After having re-do my CS (and others) and spending XP and pondering the best way to spend my XP, I would pray to the powers that be that I not be made to go back and re-do all the sheets again that I just spent XP on to increase stats.
Steven