It was a mark of pure trust that she allowed him in her mind at all. One didn't survive being a Death Eater as long as she had without learning to shield their mind at least a little. In his prime, Lord Voldemort relished digging through the thoughts of his loyal followers with his cruel, painful version of Legilimency. Instinct and self-preservation taught her to brush up on Occlumency. Though never as strong with that magic as she would've liked, Hermione knew enough to keep her alive for twenty years longer than most expected to her live. Dropping all barriers for Mr. Akingbade to take a peek inside went against all of her suspicious inclinations.