Whatever. What's wrong with giving yourself a relatively hidden reminder of certain points you want to remember to cover? As long as the delivery and content are good, that's what counts for me.
For the record, I didn't even care that Rock did it. I'll be lots of guys have done it in the past. Cena pointing it out is what annoyed me, since he was probably ahead of time told to do it to try to establish the 50-50 split (in which case the deck is stacked against Rock), or he just went into business for himself and called him out for a probably pretty established trick of the trade for the sole purpose of making him look bad, in which case he's an unprofessional douche.
Delivery and content. Don't care how you get there, long as that's good, I'm happy. Oh, and demeanor is important as well-your body language during a promo is a big deal, but if no one can tell you occasionally glance at your hand or arm or whatever (and let's be honest they couldn't), again, not a problem.
More annoying than Cena were the fans afterwards who tried to be funny on internet forums by mentioning it constantly "LOL you remember the Rock promo 1998? I bet he did the same thing with the notes" or "oh no now the Rock is not entertaining anymore! I see now his promos in 2000 with different eyes!". More annoying than this one are now the people in this thread who post large Jericho pics on every page stretching the screen
And yes, Cena was an unprofessional douche by mentioning it