is my boyfriend hiding something??

So last night my boyfriends phone went off and I asked who it we he told me it was his ex girlfriend I said why is she calling he goes I don't know why I'm like well have you guys been talking he said no and I really didn't believe him when he told me that because I have caught them texting before so I asked to see his phone and he told me me no so then I really felt like he had something to hide so I went to grab it from him like a crazy gf but he literally grabbed out of my hands so fast and told me that he doesn't need to show me that I should just trust him and I told him I just want to see so I know but he will absolutely not let me see he says that " I should trust him" but I feel honesty he has something to hide and ofcourse a million things run through my head how would you feel? Would you feel like he has something to hide?