I have observed that Opera will fairly-consistently do it, not just here but on other websites as well; and that Safari and Firefox generally will not do it on my system.   I suspect that it is therefore pretty much has to be a browser bug.   I simply try to remember to check the post one-more-time for garbage at the end.   (Removing that garbage always works; no other garbage reappears.)

bage reappears.)   ;-)