Sometimes places and people change dramatically with the distance of time...even if they don't change at all.
Perceptions of your reality all share a piece of common ground. They are your perceptions. Based on your environment, your memories, your situation. Everything we see throgh our eyes is subject to interpretation by our own brain. The curse of the perfection-seeking artist is that he can not control the perceptions of his audience. Therefore, he can never perfectly portray any thing...not a color, not a thought, not a sound.
The same holds true for the times we share in this world. You have pleasant memories of a place for many reasons, and not all of them have anything to do with the place.