FWIW, the AI sometimes has cards that can damage your creature (e.g. chaos seed and pandemonium can both do that and are both reasonably likely to be in an AI entropy deck alongside maxwell's demons) and I believe the AI knows how to damage a creature then paradox it (all in the same turn).
However, if you're sure that isn't what happened, then I've got no idea and you've found some bug I've never seen before personally.