One thing I can deduce, FWIW, is that the baby is obviously not being breastfed. My wife would have never have left either of our children with me at 3 months while she went off shopping because (1) I would not be able to feed them, and (2) her breasts would become painfully rock-hard with milk.
The moral here? If you don't want your infant left alone in a Toys 'R' Us, you must breastfeed.
Or, do what I do and invest in one of these:
or
So much easier to have the baby close to you at all times. Especially in stores and especially at this time of year. I did the whole leave the baby in the bucket car seat for the first few months. Banged my shins, strained my back, and struggled to get the car seat to fit in shopping carts, etc. Boy was that silly. Now I just throw her up on my back or against my chest and I'll never worry about leaving her somewhere.