No, you were just lucky to get a decent radiator! My first one instantly leaked just like that. It went back and was replaced. The second one showed the leak in a day or two. A third one was sent, I kept hold of the second. The third leaked straight away. I had the second fixed and it‘s been fine for the past 8+ years. I still have the third, basically unused but still with a leak, for when the need arises.