Does your partner hide their phone?

I have noticed that every time I touch my fiancés phone he freaks out and snatches it from me. Now, for example when I say "touch his phone" i mean just when I pick it up to move it out of the way if it is on the bed etc. However in saying that, his phone is usually always in his pocket. 
His reaction each time I "touch" his phone makes me feel really uncomfortable like he has something to hide. Yesterday I tried to express my feelings about this to him, but he got defensive & thinks that I want to look through his phone to find something or that I'm trying to annoy him. (I don't know why he seems to think that)  
I trust my partner and don't believe he would ever do wrong by me, but I don't understand why he reacts so weird or why it is such a big deal when it comes to his phone. I leave my phone around the house and don't have a problem with him "touching" it at all
I get that everyone needs to have some sort of privacy, but this feels really strange to me. 
Is anyone else experiencing something similar to this? Could I have your thoughts and advice please ☹️