Toys making noise when nobody is around to play with them is a pretty common “ghost” encounter. We had one ourselves with a Sesame Street Ernie doll that would randomly say “I feel great” in an empty room , in the middle of the night, etc. caught it on video once triggering with the doll just lying on the floor.
Turns out when battery voltage gets low (but not yet dead) this can happen in a circuit. I swapped out the batteries and our ghost never came back. Not surprised to hear it happening in a store where stock just sits there for a long time.
Pretty creepy though to hear that when you are lying in bed