Leak at Speedo Cable???

When I disconnected the cable I did not let it hang down and drip because it never occurred to me that some of the oil would work its way up the cable. I did not install the seal myself. I purchased an assembled unit from Brewer's Performance, but the seal did look correctly installed.

It is the original speedo cable and works for the most part (needle bounces a bit), but based on everyone's advice here I think I'll just leave it as is - thanks.