I got the same thing, but it went away after I exited and restarted the game. The yellow exclamation point didn't show up again.
Modify that. My Listintira account had 2 defense losses and then when I went back to the main screen the yellow exclamation point was there and when I checked that, it showed no defense victories or losses. I exited the game and am going back in to see if it's there. It's OK.
Apparently the extra exclamation point will show up after you've been invaded, but will disappear if you exit and go back in.