Snuffles doing tricks

I don't want to tempt providence ,but since early November she has been great.
We both feel there has been a change in her temperament,she is much more approachable and cuddly.
We don't have a problem getting her collar and lead on and she is generally more calm.
She will be 3 in June and we wonder if doggy lovers can tell us is she just maturing a bit.
The only slight problem is that she hides tit bits all over the house and if we go near or try to get it from say, under the couch she growls, we know when to leave her and wait for an opportune moment to get it
Any help gratefully received
Campbell