Yeah, I think most riders have some trouble with the canter at times. I went out today and we did several long canters. Going for a long time helps because it allows you time to kind of settle and to realize that you can canter and think at the same time. I found myself thinking about the different parts of my body and checking in to see if I was all good. Sometimes , I felt myslef coming off the saddle and I knew that I had stopped being loose in my hips, so I'd fix that. Then, I'd feel that I was about to lose a right stirrup, so I knew that I was gripping up on that side (old habit) and i'd drop that leg down.
So, if you can canter for a good long time you will have time to change some of these things during the canter, and you may need to change them over and over again. I think most average riders have moments that are really good and some that aren't and it's just a matter of making the good ones more and more frequent.
But, I've been riding for 11 years and I still get a little nervous at the canter.