There are two seals it probably is the upper seal. Usually most people change the seals when they replace the timing belt. Most of the labor is pulling the timing belt, fanbelts and the crank housing or pully. I know my dealer charges me an additional $30 to do the job with the seals. I think the seals are $7 a piece. If not your looking at 1.5 to 2 hours labor. So if it isn't leaking too bad and you can hold off till the timing belt needs changed (every 50,000 miles) I'd wait till then.