Stick your finger in the soil at least an inch or two to see how wet the soil really is. If you haven't watered in two weeks, it may need it. Dampness at the surface is usually a good sign of how moist the soil is but sometimes misleading too (the root ball may be dry as a bone).
As horsefeathers recommended, you can pull the entire plant out of the pot but before tossing the soil and rinsing, check the roots to see if they are healthy (no need to toss soil if you don't need to). If they are rotted then do heed the advice given.
PS - peace lilies are tough as nails. I have 3 now, all funeral plants (my grandmother 1985, my brother 1997, and now my dad 2015). The first two I thought were goners from 1) not watering and 2) then over watering. I threw both on the compost heap as they looked too far gone to even think about saving. The next spring, my wife wanted me to move the compost heap to another location so I started to dig and wheelbarrow the pile load by load to the new location. About 12 to 18 inches later I saw a sprig of green. What is this? I unearthed it carefully and it was one of the peace lilies. A little more digging and I found the second one sprouting new leaves as well. So these two plants sat buried under several inches of leaves, soil, and grass clippings all winter (six months) and acted like they were waking up from a long winter's nap. This was probably ten years ago or so and I still have the same plants today. Anyway, don't fret the small stuff and it is all small stuff.
