I always have characters roll in front of me. That way there is never any doubt or suspicion of cheating. That way you never have to be in the akward position of asking soemone to reroll or having to play the game with unneccessary or unfair suspicions.
But the scores you mentioned are not anything I would worry about. They are respectable, but hardly godlike. I once had a player who rolled 3 18's, a 16, 15, and 12! Now that is something to gasp about.
And also keep in mind that a characters ability scores really make very little difference overall. Even an 18 gives a meager +4 bonus. That is a helpful bonus, but largely insignificant in the overall scheme of things. People place way too much emphasis on their ability scores. In reality it's one's feats, skills, class abilities, spells, and gear that win the day, not their attributes.
If you are really that concerned about it, you may consider using point buy instead of rolling. That is really the only way you can control what your player's ability scores are, and it seems to me that you are very worried about things getting out of control. If you want to have the randomness of rolling then you must accept that some characters will have higher scores than others.
But the scores you mentioned are not anything I would worry about. They are respectable, but hardly godlike. I once had a player who rolled 3 18's, a 16, 15, and 12! Now that is something to gasp about.
And also keep in mind that a characters ability scores really make very little difference overall. Even an 18 gives a meager +4 bonus. That is a helpful bonus, but largely insignificant in the overall scheme of things. People place way too much emphasis on their ability scores. In reality it's one's feats, skills, class abilities, spells, and gear that win the day, not their attributes.
If you are really that concerned about it, you may consider using point buy instead of rolling. That is really the only way you can control what your player's ability scores are, and it seems to me that you are very worried about things getting out of control. If you want to have the randomness of rolling then you must accept that some characters will have higher scores than others.