problems with treats

Some treats are fine, peanut butter, small pieces of fresh cooked meat, small pieces of cheese, and a couple of store bought treats that can be broken up really small. She loves her kong, whether frozen or not, and it usually has a mix of peanut butter and pumpkin in it.

But if I give Ruby a treat that is too big or any type of biscuit of any size it seems to really upset her. She loves slices of pear if I freeze them first, but if I give them to her unfrozen she has the same problem, and with almost any store bought treat. She will walk around with it in her mouth for ages, whining, until she finds a place to hide it. Then she will keep wandering around whining until she goes back to it. Sometimes she will eat it after that, but more often she will pick it back up and find another hiding place, whining the whole time. She will go through it several times, sometimes ending with it staying hidden and sometimes she will eat it. Most often it has gone on too long for me to listen to the whining any longer, so I distract her with something else and remove it. She never goes back to look for it after that.

Of course, I will just give her small treats, and I don't mind that she doesn't go crazy over store treats because I know I can make things that are better for her, but I don't like how anxious she seems to get.

Has anyone else had any problem like this?