Yes. This can happen. I believe that I come off very ISTJ if I'm with a group of new people (or with 1 new person) and I don't feel comfortable using Ne with that person. There are a lot of people who find Ne to be a bit whacky and if I'm around people who I'm not super familiar with and who I know I can't really use Ne successfully with, then I just rely on Ti and Si.
I've known people for months and never used much Ne around them. And then one day I'll do something or say something "out there" that is very Ne and they're shocked. One friend (ISFJ) even said something like, "You always seemed so stable (LOL), responsible (LOL), and like you weren't much of a risk taker. But, I'm finding out that you have an unstable, risk taking side to you." Yes, I suppose I do, but a lot of it is just Ne that she hadn't seen before.
The other thing I would add is that when I do this, I don't think I make a "bad" (or failure) version of an ISTJ. I can pull it off quite well - and be very organized, responsible-seeming, non-risk taking, etc. I can do it successfully. I just find that it bores the living daylights out of me after about one week. I have to be able to "break the chains" and take some risks and talk about crazy stuff or drive to the airport on a whim on a Wednesday night and fly to Vegas with no planning whatsoever. Doing something spontaneous like that is not "irresponsible", as my ISFJ friend would have me believe. It's just not something she would do, therefore, she slaps a negative label on it. I just know that when I stay in ISTJ mode for extended periods of time, I start to feel very suffocated, frustrated, and bored to tears. I feel very "inside the box". I have to let Ne loose from time to time and it's like a huge breath of fresh air. The more "free" that Ne is to roam, the better I feel.