Actually, it does matter on a facemask. The rule used to be two-fold. There was the 5-yard facemask penalty, for essentially any time someone touched someone else's facemask; and then there was the 15-yard personal foul variety for when someone grabbed it and twisted or pulled or whatever. They got rid of the 5-yard variety a few years ago, and the intention was they were getting rid of the penalty for when someone just briefly and/or accidentally touches or grabs someones face mask.
Sadly, as is far too often the case, most refs I've watched are completely clueless on this rule (as they are, disturbingly so, on quite a few other rules) and instead have just made it so any touching of the facemask is a 15-yard penalty. This was not the intention of getting rid of the 5-yard facemask penalty, to make all touching 15-yards, the intention was pretty much the opposite, to make it so brief or accidental touching or grabbing of the facemask was no longer a penalty.
This is exactly how the rule reads in the NCAA rule book:
ARTICLE 8. a. No player shall continuously contact an opponent’s face, helmet (including the face mask) or neck with hand(s) or arm(s) (Exception: By or against the runner). [S26} b. No player shall grasp and then twist, turn or pull the face mask, chin strap or any helmet opening of an opponent. It is not a foul if the face mask, chin strap or helmet opening is not grasped and then twisted, turned or pulled. When in question, it is a foul.
As you can see, it requires either continuous contact, or requires for the player to grab, and then twist, turn or pull. On the play in question, from what I remember of the replay, Josh Kalu was grabbing the Fresno State WR to tackle him, and as he wrapped his arms around to tackle, his hand briefly caught on the facemask and then let go. He didn't grasp it and then start twisting, turning or pulling; he simply went to wrap up and accidentally got the facemask for a second. However, since the clueless zebra striped idiots were constantly looking for crap to call, the flag came out immediately. Compare that to later, when Jordan Westerkamp was being tackled and the guy nearly ripped his helmet off his head, and the ref standing right there (who may have even been the very same ref) just stood there, no flag thrown. It took Westy complaining, and then a ref behind the play throwing a flag to get it called. Even then, they had to discuss it for a while, probably trying to come up with some reasoning to pick up the flag.