Do you think in Japanese?

Some time ago, one of my cousins asked me if I still think in Japanese sometimes. I answered that most of the time it's not really an issue, as I tend to have "modes," and when I'm surrounded by and using English, that Japanese switch is generally off. Lately, though, I'm starting to reconsider that. Maybe it's because I am trying to expose myself more to Japanese these days, but there are definitely times when certain Japanese phrases come to mind, and I kind of cut off the impulse to vocalize them.

I think the most common ones are words/phrases like:

仕方ない/しょうがない (It can't be helped; oh well)

すみません (sorry; excuse me; thanks)

そうか/そうなんや (I see; Is that so?)

そうだ(that's right; yeah)

まぁ (well...; meh)

I don't really know what the deal is, but I'm guessing it's happening for me mostly with words that aren't strictly translatable into English and have different nuances or applications (or levels of naturalness) than what you might say in English.

Any thoughts from you expats who have returned home or moved on to another country? Has this happened to you?