In addition to other useful information given earlier: yes, some "older" faculty are very sensitive (I almost wrote "hyper-sensitive", but that would have been judgmental...) about electronic devices of any sort in the classroom. Thus, no matter what you're doing, even if it's note-taking from their lecture, it will upset them.
Some of that reaction is due to the greater difficulty of telling exactly whether you're paying attention, or not. The point is that most other "inattentive" activity is more easily distinguished from "attentive" activity... so that part of what is upsetting is that it's no longer possible to easily distinguish.
Indeed, when I was in high school, one of the great attractions of my hobby of mathematics was that writing technical-looking stuff in a notebook looked just like taking notes in class... which was a great trick for me, personally: make occasional eye contact with teacher, then go back to what I was doing. :) An astute chemistry teacher did make a very cryptic comment which I only later realized was meant to let me know that, although no action was taken, not everyone was fooled. :)
But/and, in fact, "even many old people" realize that "paper" is being significantly supplanted by electronics. In my graduate courses, students have the PDF notes called-up on their tablets, and mark on them using the touchscreen corresponding to the "added value" I (attempt to) provide in my lecture/discussion of the material. This is entirely reasonable, and certainly preferable to everyone printing out their own copy to physically mark on... ?
Similarly, if/when I give references during lecture/discussion, how could I discourage a person from looking up the reference document (assuming it's available on-line)??? I realize that a well-prepared student may often have "extra cycles" available, so that they can legitimately pay attention well-enough, while looking up the peripheral stuff...
And, similarly, in fact, I realize that a well-prepared student can fully follow what I'm doing while intermittently carrying on an email/facebook/text-message discussion with friends. Why not? Is this worse than daydreaming, looking out the window? :)
I think the genuine operational issue is not whether-or-not faculty are offended, to which the answer is something like "yes, but that's not the only thing that offends faculty, ...", but whether it would be genuinely appropriate to try to actively prevent or "police" electronics use in class. This seems like a hopeless battle, beyond the larger request for ordinary civility in all things.