I lived in CT up until college and my entire family lives there. I went to school OOS and chose to gain CA residency for a shot at a CA medical school, so I am under this same umbrella of OSS applying with strong ties to the state. With so many applicants applying broadly to many schools they dont care much about, I felt this was necessary to mention to stand out in that regard. I worked it into whatever their version of the "why our school" essay was. I believe theirs was something like, "how can UConn help you in your medical career." I mostly talked about what I liked about their school and how it would help my medical career, but I also discussed the benefits of being where I grew up and being close to my family.
That being said, in your post you said "should have mentioned," does this mean you already submitted? If so, don't think about it anymore since you can't change it now. It will only bother you and this process is already stressful enough. I'm sure that ties to the state don't matter too much and by no means will make or break your application. If you get an interview though, find a way to mention this.