Thanks for the input all. I think what @Bryce is describing is what might have happened. Have been using the Ipad app lately. Then when the ipad wasn’t in the trainerroom, but my laptop was I quickly grabbed that and effectively only turned on the internet connection after my workout was over (I think). The laptop must still have had my previous FTP setting, and synced that to the interwebs.
Luckily not much harm was done as the difference between FTPs was only 2 watts 
I’ll delete the ‘newest’ ftp update and only keep those from the test.
Thanks for confirming that FTP should only change automagically after testing, all others changed are ‘manual’ (or artifactual in this case).