I did exactly the same.... and believe me no question asked.
We checked in together at the immigration (Pearson airport).. the officer just asked what is our relation with each other and how long she is staying in Canada. Other than our passports and my PR card, nothing was asked. In the end, the office told us that in case my wife changes her plan and decided to stay more than 6 months, let CIC know three months in advance and they will facilitate for her extension. However, she just stayed here for 2 weeks then returned.