Overprotective of his phone

UPDATE: Well I talked with him and he says that its because his ex used to go on his phone and change and delete things without his permission so now he's protective of it.

Also told him that if he wants to go through my phone then I should be allowed to go through his.

Thank you Ladies!

I don't know whether this is a legitimate thing or if I'm just overreacting. So my boyfriend is VERY protective of his phone. I mean won't even let me touch his phone. And he always keeps my phone in his pocket. Like if I get up for something he'll take my phone while I'm up and go through it then put it in his pocket. It's really bothering me. Is this something I should keep an eye on or don't worry about it?