While ball python locks can be very long, they can happen in only a few hours, so yes, while you were sleeping, there is a chance they could have locked up. There are cases of snakes retaining sperm from previous seasons and even cloning themselves and becoming gravid without ever coming in contact with a male (though this is extremely rare). Though given the history of the female being in with a male for periods of time, I would guess she bred while you were not looking.
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