The front seals will be fairly inexpensive to replace, the rear will be more expensive though ( have to remove the tranny). The seals I think they are talking about is the Cam and crank seals. Unless it's leaking real bad it should not cause you any 'problems' as long as you keep your oil level correct. It could eventually get oil on the clutch plates, timing belt ect... and cause problems. I ran ming a long time leaking, but eventually they got bad enough that I had them replaced.
Zig