Herb...
K&N oil filter posts rank right up there with oil and transmission discussions/wars. Some love 'um... . some don't. Do a search and you'll have hours of reading. I assume you're talking about a drop-in filter in the factory box? Some have complained that it's difficult to get a good seal between the box and filter edge; therefore you have leakage.
Also, $10 for a K&N life-time filter seems suspicious to me... . not a flame, I've just never heard of them priced that low. The cleaning kit alone costs that much. If it's a knock-off, I'd pass.