That wasn't an online invasion, it was a scripted NPC Black Phantom invasion. I can't remember her name, but you can summon her to help you fight the spider queen thing now that you've killed her in black phantom form. There's several of those in the game, one guy invades you 3 times and when you kill him the last time, you can pick up his thorny armour which does damage on rolling. Pretty sure it does show recently encountered players on the PS3 anyway.
http://darksouls.wikidot.com/maneater-mildred