Lost points after shielding

Last night while finishing up the alliance event, I made a push for top 5 and got to 4th with 708 points and shielded immediately with three hours left. I jumped on the forums to post my position to my alliance chat, and when I went back to take a screenshot of my position, it said I was in seventh. I also had a pop up saying I had lost 27 points. I didn't think to take a screenshot because I was so stunned. IS this a glitch? Can someone that is in the middle of a battle when you shield still cause you to lose points or something like that? I still ended up top 10 and got my BP covers, so I am not mad, but I wouldn't have minded getting the extra 500 iso either.