8 year old in tears two weeks after pet mouse died

[tevion]

Hi
when his pet mouse died two weeks ago and I told him he didn,t seem bothered and just carried on playing on his ds.
However tonight out of the blue he has started wailing about it saying he wants his mouse back and that he misses it.
It has taken me an awful long time to console him and he is now asleep but is it usual for children to just suddenly cry over the death of a pet when at the time they didn,t seem in the slightest bit bothered.

I think that understanding the permanence of death is a developmental stage - it might have taken him a little while to realize that his mouse wasn't coming back.