Boyfriend increasingly protective over his phone

So, the last couple of weeks, maybe a month, my boyfriend has been completely over protective of his phone. He doesn’t have a password on it or anything and tells me and other people that I can have his phone whenever because he doesn’t have anything to hide. But when we are home, he makes sure the screen is facing down, he takes it with him where ever he goes and if I remotely touch it (even just to move it out of the way) he quickly grabs it out of my hands. About two weeks ago, at 5 am I was laying in bed before getting ready to go to work and he got a Snapchat from his cousin (who is male) and I looked, it wasn’t anything bad, but what I did notice is he had many females on his Snapchat, and they were recently added. He got super mad at me for being on his Snapchat. I asked why he had so many females and that it made me uncomfortable and he said they were mostly his cousins and some girls we were mutually friends with. So I let it go, but he’s not posting pictures of us, or our baby on there anymore, he’s constantly on it but turns his phone away or closes it when I’m around. I don’t know if I’m over reacting because of past relationships, or if these are real red flags. I leave my phone unattended pretty much everywhere. I’m constantly asking him where I put my phone, I also use him as a back up for my social media accounts because I had a recent ex try to hack my accounts. So he has all my information, and such. I just don’t know what to think and I’m not trying to jump to conclusions but its starting to make me feel like something up.