I am exactly like this as well. Some days I am just in the mood to listen to 'old' music. Music I listened to growing up. Other days, I crave something new.

I find the same thing with foods as well. When I discover a new dish/restaurant I love, I will have it several times and relish in the new flavors/atmosphere. After a while, I still love and enjoy that dish/restaurant, but now the thrill has been replaced by a more comforting and familiar association with a fun night out.

Another example, growing up, I was only allowed to drink Coke when we ate out or went on picnics, or attended sporting events. As a result, as an adult, my brain made an association between drinking coke and having a good time.