En chino, por favor

I've written before about switching between foreign languages and how it can pose some difficulty. Today I just had another run-in with a lag in switching between languages.

I was in the shower listening to my mix of five-star (according to my own personal rankings in iTunes) foreign-language songs. Now normally I tend to listen to podcasts, but sometimes you just need to get your groove on and today was that day for me. The playlist, which is supposed to be random, spit out a bunch of Spanish songs all in a row: El Niágara en Bicicleta by Juan Luis Guerra,El Último Beso by Los Boltons (a Spanish cover of Last Kiss by The Cavaliers),Esposa by Tony Vega,Estoy Aquí by Shakira,Mirando el Mar by The Sound Lovers, Buscando América by Ruben Blades,and Ciega, Sordomuda by Shakira. Naturally I was singing along with these songs, which, in addition to keeping me entertained (my wife, not so much), is a good repetition of the vocab contained in the songs.

After I got out of the shower, I had to go downstairs to tell the Chinese-speaking babysitter that she could go whenever she wanted to. As I was walking down the steps, I was thinking about what I'd tell her and I heard in my head, in Spanish, "Si quieres ir..." ("If you want to go..."), and it occurred to me that that was a bit odd. Here I was about to tell something in Chinese to a Chinese speaker and Spanish was coursing through my brain. I'm pretty sure that if that hadn't run through my head as I was walking down the steps, the first words out of my mouth to the babysitter would have been in Spanish. Listening to and singing along with those songs had put me in Spanish mode, and I didn't snap out of it until I consciously thought about it.

This phenomenon intrigues me. Anyone else who speaks multiple foreign languages ever run into this? I'm curious as to what is the relationship between this and language learning. I suppose it's a good thing that my mind just kind of switches automatically into another language, but how can I improve my ability to bounce between languages? The obvious answer is practice, but with better understanding of what's really going on in my head, it'd be easier to really figure out how to utilize this best for language learning.