SO randomly overprotective of their phone?

Me and my SO have been together a little over a year and he has NEVER been overprotective of his phone and I've never been one to go through anyone's phone but this morning I was saying goodbye as I was leaving for work and he asked me to cuddle for a few mins before I left so I pushed the "home" button on his phone so I could see the current time... he snatched that phone up like his life depended on it! Granted he was half asleep but this is completely out of character for him and to me that raises a red flag... should I bring it up to him or just let it go?