I wrote a letter to a Polish friend today. Though I'm no longer living in Poland, I still use Polish from time to time. Actually, if you asked Sasha, she would probably tell you that I use it more often then I would admit. It seems to be an almost weekly event when Sasha tells me that I'm speaking the wrong language to someone.
Though my Bulgarian is getting better, I still tend to throw in a Polish word from time to time. This usually happens when I can't remember the Bulgarian word I'm trying to say. The language center of my brain just says what it thinks is right, and by the time the rest of my brain weighs in on the matter it I've already spoken a word that no one around me understands.
It is getting better though.