Yes, these are very common PFLs. but in majority of the cases, the applicant has been refused at least 1 time in their lifespan and they didnt declare that refusal. They are usually aware of the refusal but there answers would be:
Examples:
-I thought that once I got the US visa .. the previous refusals doesn't matters.
-That refusal was before 15 years, I were a child and applied with my parents.
-I thought question is talking about Canada visa refusals only
But in your case, (as per the info you provided) your SAME application went for Administrative review and SAME application was granted. and you never received any notification or intimation of refusal.
So that is something interesting, this usually dont happen. But IRCC could be wrong or interpreted the info provided from US side wrongly.
You need to explain what happens and you never received any official refusal from US. This is why you marked the the question NO. Also not to forget, attach maximum evidence supporting your statement.
Good luck.