I don't know what the policies are like there, but here, it could potentially be seen like a T is "chasing" a client, which isn't supposed to be done. Well, I know that would be the case if a client terminated and the T was trying to convince them to come back. This is different if she stopped practicing.

But with it having been a few years, she might not think to reach out to you, figuring you'd moved on and might not want to hear from her. If you're interested in working with her again, I'd trying reaching out.