Plot hole

I just wanted to see if anyone agreed with me on this/if I’m misunderstanding and someone could explain it to me. I’m in season 3, and just watched the episodes with Zach pursuing Gabrielle. Something that really bothered me was he mentioned he was “2 months older than John Rowland” and then an episode~ish later, Lynette and Susan (I think, I know Lynette was part of the conversation but it could’ve been with someone other than Susan lol) were talking about how he had money from his grandfather and he couldn’t get it because the money was in a trust, but he turned 18 a month ago so the trust became available. My issue with this is during season 1 I feel like a largeee part of the storyline was John turning 18, plus earlier in season three she met him at the hotel and it definitely felt like he had “matured” and they were implying that he was an adult. Like I said I’m not sure if I’m just missing something here or if is just a plot hole so I’m looking for other people’s insight. Also would love to hear other people’s plot holes they’ve noticed if this is one, because now I’m wondering if there’s others that I have missed.