That's a good thing
What is your general area? The reason I ask is, this is how they are processing cases in the SIR:
CPC-M does the majority of the case processing. They will dispatch tasks to other offices. An example: I am 100% sure that SIR cases are having CPC-V process their Security and Criminality checks. Once the case has reached a point where CPC-M's officer feels it's complete enough, they will transfer it to a local VO (that's who will issue your PR when you land). They are required to do a final "Review" for Quality Assurance reasons. If CPC-M or the local VO wants to meet with you to discuss something, that's where your interview will happen.
All cases in the SIR will end up going through some degree of review. Local VO's generally have a little more time to process smaller volumes of cases than CPC-M has. So, not to worry about the review. But for the same reasons, it can vary depending on what VO is local to you how long it might take. Was there any additional document requests?