I believe you, I've only had clones do this to me, it usually starts right after theyy root... they grow numerous small side branches (tiny), looking all crazy, then a few days later the side branches start shooting up like crazy, very quickly growing taller than the top, only the top remains there so they are very obviously "self-topped." I'm not big on topping though, I usually only top mother plants. I like LST and HST techniques though, you can do amazing things with a little string (or a little branch-pinching.)