My Fur Babies Strange Behaviour

As you all know my Tiger passed to the Rainbow Bridge last Tuesday. Since then my other two furries - Tabitha and Zeus have become weird. Two cats who positively shuddered whenever I served a bowl of milk to Tiger(who absolutely demaded milk every time I made myself a coffee) are now demanding a small bowl of milk each at least once a day. And they both drink it to the last drop.
Anyone out there in CatLand know why this would be happening? I don't mind giving them the milk - after all I bought the special cat milk for Tiger anyway - I was just wondering why the total reversal of behaviour.

I'll move this to Behavior for you.

It sounds like a part of their grieving process to me.