I have had AF once back end of 2014. I use an alivecor regularly and never had AF on it. I took the alivecor to the gym and decided to look at my heart rate immediate you post stopping running. Gave several unclassified readings and then an AF reading. Once my heart rate return red to around 100 tested again and fine. Is this just an issue with the alivecor not being able to cope with high heart rate levels or a possible AF reading. Is it possible for AF to come on in excuse and then go away. Thoughts appreciated.