Lied about age? Am i over reacting?

A guy I am talking to (we are just friends) said he was 38 when actually I found out he was 30. I'm ok with him being 30, but it's just the fact that he lied about something so small like his age. I wasn't mad when I asked him "why did you lie about your age?" And at first he ignored my question so I asked again and he literally said "it's in the past forget about it" and his response is what made me mad. You can't lie to me (even if it's just his age) and not tell me why you lied to me. for me when someone lies to me it's a fairly big deal to me as trust is important to me.

Update***

I told him how I felt and he apologized and when for a 3rd time asked him why he said he didn't know me, but now he trusts me. Which doesn't make sense as he told me his name which is more identifiable than an age