Yup, not often, but it does happen. When that happens, leave the hive open, as is, just all-stop and walk away for 15 minutes. When you go back, approach the hive slowly while scanning the ground/grass and twigs around the hive for a small clump of bees. She will be in there. If no clump, then she will be back in the hive. If you stay there fluttering about trying to find her, further disturbing the hive, chances are she will stay away and not able to return.
Good luck! Chances are very high she will return if you just step back for a break.