Could somebody please explain to me why did the "Critical damage" message pop up although my mech was still having armour on all components? As seen on the picture, mech health was at 96%, that's like ~15 damage done, with 232 armour overall (so 232+119=351 total HP), correct?

From my perspective it looked like I was hit by AC20 from Victor at GAMMA (cockpit shake from AC hit), but I can't be sure, because there were lots of enemies near Citadel. Picture was taken about 2 seconds after my mech was hit. I was previously hit in the cockpit, front torso and legs from ERLL, but received critical message after got hit in rear torso.
Note: this wasn't caused by overheating or overriding shutdown, I wasn't even close to thermal barrier.
EDIT: For anyone having trouble viewing the image, here is the new link(I can't insert image directly, it says I don't have permissions on this community):
Spoiler
Edited by PanzerFurrry, 16 August 2013 - 06:47 AM.