QB as a runner

[rockyroad]

Looking for rules interp. here as a Coach...the team we played last weekend ran a full-house backfield...the QB would fake a hand-off to the fullback up the middle, and then come down the line running an option with one of the tailbacks...two different times, he did hand-off to the FB, and then came down the line faking the option. On both occasions, our D-End tackled the QB thinking he still had the ball...on both occasions, the White Hat threw a flag for UNR on the D-End...in our minds, since the QB is still faking that he has the ball, he is still part of the play and fair game...what's the ruling on something like that?