Desktop printers use very imprecise paper positioning methods and you can expect the print image to drift within a range of +/- approximately 3 mm overall in any direction, even on a long run of 1-sided prints.
I had a feeling that was the reason. I just couldn't get my colleague to believe what I said to her. That's why I was wondering why this was happening to the prints. It happened before with another print as well. It had the same 3mm difference but this time from the other side. That's why I kept getting the blame for it. But thank you for the answer.