That's normal. If you enter Canada by car from the US, CBSA will often capture the vehicle information and will not stamp/scan your passport.
It can be fixed. If you owned the car that you crossed the border in, you can submit an ATIP report to CBSA. Attach a copy of the car ownership and request the additional entries to be added to your border crossing report. If it was your friend's car, you can still attach a copy of the ownership and a written note from the owner of the car with permission to use his information and confirming that you crossed the border in that car.
BUT, I do not recommend you to even bother, because: 1) CIC is aware that CBSA reports are often incomplete and will not hold it against you, and 2) it's actually to your advantage because you are reporting more absences that they can trace, thus you are clearly being honest.
Yes, I had the same situation and after corresponding with CBSA and an immigration consultant did not enact any changes.