Lost (or temporarily misplaced?) flip turn...

If you happen to see it, please tell it to phone home... ;) Seriously... I am new at swim workouts and only recently (in May) learned to do flip turns. Tonight I was just doing an easy swim and getting in some practice doing the turns, which were going fine. I alternated them w/ open turns (not comfortable w/ flip turns in the shallow section, but that's a whole other thread). Also didn't do them every single time in the deep section, but for the most part, when I did them, they went fine. They weren't beautiful, but they were flip turns. Then I started one, and for some reason came out of the tuck before I could make the turn. I was doing this deep dive right next to the wall, and it totally unnerved me--not to mention gave me a painful leg cramp which I managed to stretch out. At first, i was just going to leave it at open turns for the rest of the swim, but I didn't want to leave feeling defeated, so I tried again a couple more times, got something that looked marginally "flip turn-ish"--but I'd start the turn too far from the wall, and the flip wasn't quite right. They seemed more like my first attempts when I couldn't get them right--before my coach worked with me on them. (He's away for the summer, so I'm working pretty much on my own now until the fall when the masters' group starts back up again). Then I thought I'd try one more time (swim was almost over by this time) and got that same totally mangled turn deteriorating into dive that I mentioned above--again w/ the leg cramp. At this point, I decided to call it a night. My concern is that I've gotten too spooked and that next time I swim, I'll have the same problem. But obviously, it's important to keep one's focus positive and not let this incident throw me. The lifeguard (a serious swimmer herself) said she thought it might be tiredness. Could be... or stress. Another time during a practice, a team-mate noticed that I seemed to tense up just before the end of the pool, and I think she has a point. I know that when I see the "T" that marks the end of the lane line--especially if I've decided to flip turn, there's this moment of fear--I got to where I was able to slip past that fear, have tried to relax, remember what my coach told me, stay focused on that. But the fear is always there. I see people dong flip turns so easily, so seamlessly, and for me, they still feel foreign, even tho less than before. But tonight, I felt like a complete beginner again after that one turn gone bad. Your suggestions welcome!