The amount of oil poured into the crankcase will affect engine oil levels. Each vehicle manufacturer will list a specific amount of oil that needs to be used. The amount of oil a vehicle requires is dependent on the size of the engine, and the oil pan. Providing you have not over-filled your engine with oil, a high reading on the dipstick is possible. When a vehicle is mainly used for short duration trips, and stop-and-go driving, the engine, and the oil never get a chance to reach temperature. This causes moisture to build up in the oil, and artificially inflates the reading on the dipstick.
For more info, see How to Check Engine Oil Levels