"Account Security Tip" message: could this be an infection??

This morning, I woke up to find, on my Windows 7 machine, a message bar at the top of my Google Search tabs (in Firefox) saying:
ACCOUNT SECURITY TIPMake sure your recovery info is up-to-date with a 2-minute Security Checkupand with two buttons on the right-hand side, one saying "START CHECKUP" and the other saying "NO THANKS". I have checked my other two devices, Windows 10 and XP, and neither of these shows this message. I googled this, and found nothing matching the exact above text, but I did find this page: https://productforums.google.com/forum/#!topic/chrome/VmrAyQuYY7E . After googling similar queries to poster RJ897's from the aforementioned webpage and subsequently refreshing the tabs presenting the message, the message has now disappeared. Is this an infection (or an aggressive PUA that has somehow smuggled itself onto my machine?), or is it a genuine Google message?? If the former (infection/PUA), this will be the first time in more than 10 years of using Prevx->Webroot that I have found an infection on any of my machines. If the latter, the message is frankly badly designed by Google as the way it presents itself naturally invites suspicion. Any feedback on this will be welcome.