Okay, so I faced this situation before. I can tell what happened and how it affects my life and immigration situation.
I have a US B1/B2 visa, a business/tourist visitor visa. I wanted to get a new WP at the border. I went to the border. Went over to the US side. They asked if I had an I-94 (iirc) form in my passport. I did not or it was lost. So off you go to the immigration building and get one of those. I went there, they asked why the hell you want to go to US of A? I told them, visit, some shopping and back to go to Canada. They asked, are you flagpoling? I told, I will apply for my WP in my return journey. They gave me a white slip, called administartive refusal and told me to go back and show it to canadians. I went back and got my WP. Cool!
Now it is important to remember, if they ask you upfront if you want to do flagpole, you can not lie. /it will get you in trouble. simple.
Now that white slip is administrative refusal. And you need to remember it for life long. It is still a refusal. Does it leave any entry in the system? I do not know. I do still mention it in any form that I fill for any country where I try to get their visa. i did mention it in my canadian PR.
So if you have that form i-94 or whatever you are golden. if not do remember the administrative refusal thing.