A fragrance product can smell a little different after it has been stored because aromatic materials interact with the product base and because some volatile components can slowly change or evaporate over time. Temperature, light, and exposure to air can speed those changes.
That is why good storage matters. Keep home fragrance products closed when possible and away from excessive heat and direct sunlight. Small changes do not automatically mean a product has gone bad, but a fragrance that has been sitting in harsh conditions for a long time may smell less vibrant than it did when it was fresh.