"no call" mechanic

[Troward]

NFHS: I was watching the varsity game after my JV game yesterday and on several plays where there was incidental contact(one time a collision) and then when the official passed on a block/charge call; the official used a signal that looked like the "not closely guarded" mechanic. I asked him about this in post game and he said he wanted to make it clear that he saw the play and was ruling the contact legal.
I'm wondering if other officials use this "technique" and if I should?
I believe this signal is not even approved for NFHS in legitimate "not closely guarded" situations let alone for these other plays?

thanks
GTW