There's some science behind your faster weight loss. I first experienced this myself when going to my first wedding a few months after going primal. I had been pretty strict leading up to it, and planned to stay the course and enjoy the variety of meat and veggies available, but the Bride's sister (also a close friend) had gotten into cake-making and wanted feedback. I said screw it, never really been one to micro-manage my lifestyle (more on this later) so I went for it. The next day I had "lost" about 3lbs, which was huge at the time since I only ever had about 25-30lbs extra (and to date have lost and kept off about 28lbs. I'm a small guy close to my 'ideal' weight) when I was fully expecting to have gained some after the previous day, where I also had a few drinks with tonic, which is a pretty sugary mixer.
Go find the carb-refeed threads, run a search for "carb-refeed" and read ChocoTaco's explanation for why "binging" on carbs can produce weight loss after restricting them for some time. Note though, that carb choices are VERY important and the sources you described above aren't the ideal ones.
Anyway, here's my take:
a) There's some actual science for this, so go find the threads I mentioned as I'm not as eloquent with explanations for it.
b) Cortisol, the stress hormone, plays a huge part in a lot of things, body composition (ie: whether you lose/gain, or 'how you look') is directly affected by cortisol. If you notice, your account is full of positive connotations, you don't seem to "sweat" the instances where you "cheat" so naturally this doesn't stress you, cortisol stays low, you lose weight. On the other hand, some people flat out hate themselves after eating something outside of paleo/primal guidelines (THEY'RE NOT RULES) cortisol shoots up, these people may take measures to counter their "bad behavior" (fasting, exercising, etc) which further stresses the body, cortisol keeps rising... you don't lose any weight. Mindset is VERY important. Obviously, this isn't to say you should run to the nearest shit-food and down it and smile about, and do it all the time, but occasional indulgences are better had when one is happy about it, rather than not. Eating a burger with fries and a bun is something that for instance can make a social situation seem easier, your friends won't give you shit, etc and you'll be relaxed through the experience. You can of course just go bun-less, order veggies, and still feel good (as you should) but if YOU want to indulge (not just to cater to your friends) then by all means. You're already better off not eating it for breakfast, lunch and dinner, so some isolated instances are good for the soul.
I probably indulge in shit far too often, and my progress has stalled many times as a result, so I'm not advocating doing this all the time.