I think why this raises a red flag for me is because her behavior is aberrant. Her attention should be focused upon you--that's a therapy norm. Then her saying that she'll "try" to not touch it, but will not put it out of sight, is an indication that it is a behavior that she knows is aberrant--but she won't own that, and instead, masks it at your expense.

Making unreasonable demands about T behavior that falls within therapy norms should be questioned. If a T sits quietly with crossed legs, and you were to try to insist she uncross her legs because your Mother used to sit that way and it bothers you--that is a request that should be explored, not accommodated, at least not automatically, because it falls within therapy norms. But her phone behavior is violating the norm, and if it were you engaging in the behavior, your T would be right to challenge it. The power play aspect of the masking is what makes this feel dishonest to me.