You won't always catch them locked, but it doesn't mean it isn't happening. Make sure you aren't checking on them too often, either, because it could be distracting.
Oh, and it's always recommended to double-check the sex of both snakes, just in case!
having pretty much the same problem with my cinny male. He bred to one cinny girl and now has not bred since to the other two cinny girls or the one he first bred with. still early so im gonna wait another month before i re introduce him again.