Had a final interview for a manager position at a large Canadian firm and didn't talk about salary at all. I discussed in brief salary expectations during my first phone interview with the recruiter.
Is it usual for this to happen?
Yes, this is normal.
Interviews are for one purpose - to determine whether you want to work for the company, and whether the company wants to work with you (in other words, is there a good fit between you and the position/team). Salary expectations are a part of what makes a good fit, but it sounds like you've already discussed that.
After a good fit been established, the company and you enter the negotiations phase, where you discuss your compensation. Until the company has determined you're a good fit, there's no point in negotiating.
Sometimes, a final interview can transition into a negotiation, but this is not a requirement. If there are more people they need to interview before picking the best candidate, it's simply too early to spend energy on negotiation.