Interesting... This does not occur for anyone in our raid groups. Were you dropping out of combat using a stealth ability or something? This would cause a combat end event and a combat start event in the log, resulting in a new "fight".
Please keep an eye on this and if it continues to occur feel free to submit a bug report online or shoot the support email address (found in the help window of the app) a message with your log attached!
Nope, it happened for the 5 people trying it out and none are stealth. But we'll be using it more because we like it so much so I'll let you know!