Am I tripping??

So my fiance is the sweetest most loving person ever but becomes a completely different person when I take his phone. I joke around sometimes and take it acting like I want to look through it or say silly stuff like let's see what hoes you talking to even though I know he's not actually talking to hoes, which him and his Mom are super close so I know 9/10 he's talking to her or his best friend but his actions/reactions make me think he's hiding something because I honestly feel like if you have nothing to hide then why do you act like a crazy person. Or if I need to see his phone because mines dead or whatever he's looking over his dang shoulder to see what I'm doing to the point where I just give him his phone back. So what erks my nerves is when he lies about stupid stuff for example if I'm staring at him pick his nose I'm like eww go get a napkin or something and he'll lie and say he wasn't picking his nose I mean swears up and down he wasn't...like HELLO I literally was staring at you for 5 minutes doing it why are you lying! .... it's not about picking of the nose it's about if you can lie about something sooo stupid then what else are you lying about? Soo am I tripping??