If you don't stutter in some situations and you do in others, is that an indication that your problem may be psychological?

If you don't stutter in some situations and you do in others, is that an indication that your problem may be psychological? I've been reading John Harrison's book Redefining Stuttering and it got me thinking that the problem could indeed be largely psychological, along with my own personal experiences. If it's the case that you don't stutter in some situations or you've gone through comprehensive training in avoidance reduction of words and situations that you don't really stutter anymore, would that suggest your issue was psychological to begin with?