Depends on how loud it is. Fords often have a pump whine which is usually normal, unless it is real loud. Some aftermarket pumps don't whine, so don't know why Ford's do.
Sometimes a fluid replacement will fix it.
Ah!!! and I just remembered, my local Lincoln service guy just did a TSB repair on my 04 LS. There is a TSB on pump whine and squeel. This is sometimes an indication of future rack and pinion failure $$$. So you should take it in to be sure this isn't your problem. If your car is under warranty, this repair is covered. They essentially remove some of the fluid and put in some friction modifier if I recall.
Good Luck,
Jim Henderson