@tomgoph1234 there are a few possible reasons why you weren’t denied. The most obvious would be that, despite your 18 ACT, your application wasn’t weak enough to reject. However, you should reasonably expect a waitlist as the one piece of objective information you’ve provided them is three points below the national average. Sorry to be the bearer of bad news on that and I truly hope I’m wrong. But that’s why I asked you about a Plan B.
Your GPA and PSEO courseload are fine if not superb (a 3.8 unweighted with 15 college courses is truly admirable). Given these attributes the 18 ACT seems way out of place. If I were an adcom I’d be scratching my head. Did you provide them with an explanation?