Inland Sponsorship - AIP INterview - Decision to be mailed??

Dear All ... me and my wife were called for the first stage interview at Etobicoke office today. I am a PR and have sponsored my wife. We went to interview with our 3 months old son. According to FOSS notes they wanted to make sure if our relationship is genuine as we only had a 2 months of courtship before we got married. Interviewer only asked 2 open ended questions:

1. How did we meet and our relationship progressed?
2. What are our future plans?

We tried to answer in detail but weren't sure how much detail we needed to provide as she didn't ask any followup questions. She kept on saying if we wanted to add anything else but didn't actually ask any specific questions. We gave her after-wedding photographs as she already had pictures of our wedding reception and other outings before marriage. We also gave IO a printout of most of the emails we had exchanged for the first two months til we got married. This is something we didn't submit when we had filed for the application.

She told us that she will review all the information and the new documentation we had provided (emails + photos) and will mail us the decision. We were both surprised as we thought the decision is generally made on spot.

Is this something usual?