Found out boyfriend lied about age

Today I was with my boyfriend while he was setting up a new accounts for electricity and gas because he's moving. When he gave his birth date to the person I realized he lied to me about his age. When we first met he told me he was 32 when were texting. I'm 23 and never really thought I would date someone with a big age gap but I adjusted to it. When we went on our first date it was right after his birthday and I was like oh so you're 33 now and he was like no he just turned 34. He must have typed it wrong in the text message. I was like whatever no big deal this is the first date we're getting to know each other.

Fast forward 7 months. We're really close. We've survived arguments. Been there for one another. Supportive. And I now find it he's actually 35. I'm upset. Not really about the fact that he's a year older but that he looked at me and lied to me and never thought to come back and tell me. I'm sure I've brought up his age several times in just casual conversation. He has gone on and on about how he's working on trust and developing trust but he lied to me. I've been making a point to be really open and honest because that's what is important in developing a relationship. He says he just doesn't usually like to tell people his age. It's a personal thing and a trust thing. I just imagined getting to his next birthday and me celebrating the wrong age.It was crazy to me. He apologized for hurting me.

I know I'll get past it but it was so upsetting. I didn't give him as hard of a time as I wanted to because his dad just passed this week and I didn't want to add to his stress. But is my anger and frustration reasonable? Is lying about his age a normal thing? Am I taking it out of proportion? I don't know. I just couldn't understand. He's known my age since day one.