I've seen the exact same thing happen to one of my queens too a few years back. I believe all I was doing was putting her in a cage when all of a sudden she froze stiff as a board and wings outstretched, I thought she was dead. I remember saying to myself 'great will, you just gave her a heart attack' but after a few moments she started twitching at which point i monitored her. she eventually was introduced into another hive and did fine but it was the darndest thing I'd ever seen. intresting to say least.