Is this natural behaviour? Acceptable?

Im a mother of two and after 7 years of marraige, my husband has started hiding his phone from me. He has put a password to his phone and refuses to let me see his phone... I feel so hurt... Is this natural for me to feel hurt, or am i over reacting? A relationship should be transparent right? Is this the beginning of whats to come? If so, how do i deal or correct this? Pls advice...