Shouldn't Last Chat be, when the Contact's last responce to you was? not when you last Chat with them, I don't know if it was meant to be this way or not.
I'd rather know when they last spoke to me, I guess... why would it matter when you last chatted to them, it could of been a few days ago, it could of been a month ago... it could of been five minutes ago, but you always have some idea when 'you' last chatted with them, if you aren't logging... knowing when they last spoke to you is difficult to remember though