First, check your fluid level, and top off as needed. Second, drive around for a while, and then check the fluid level and see if it's low. If it is, you have a leak, but it may not be coming from the p/s pump, it may be coming from a high pressure p/s line. Check the pump to see if it's wet, if it is, make sure its p/s fluid and not your valve cover leaking (you'll be pretty pissed if you spend an arm and a leg to have the pump changed only to find out it was just fine). If the pump is not wet, check all of your lines from beginning to end and make sure all connections are good. Hope that helps.
Danny