Seemingly, they also have some sort of canary in place in case they get secret requests under the patriot act: http://boingboing.net/2013/11/05/apple-hides-a-patriot-act-b...
It was removed for the latter half of 2013, and this just-released first half of 2014 report.
Take that as you will.
By omitting the line you are, for most intents and purposes, saying that you received a request. Now, saying you received a request and saying specifically what request you received are different, but I imagine the gag order doesn't make that differentiation.
Gag order is not that you can't say a specific thing, it's that you can't communicate a specific piece of information. The canary is communicating something.
A court order can ask you to lie, so the "I can't lie to my customers" defence probably won't work.