Does this happen regularly or was it a one time thing? Are you interested in this person?
If you notice him looking at you often then I do think he is interested and at the very least finds you attractive. He would not make it a point to do this if he did not. He even came next to you in the aisle purposefully. I do think he notices you. What he wants moving forward I can not say, but since you are interested as well I would may be purposefully go on his line, ask him for help, or etc.
He may be shy as well. I think as you see him more and make yourself approachable it will be easier for him if he were to ask you out or start up conversation. If he is looking at you often and you notice him going near you these are all signs. However, over time you should see this increase and he should be starting up a conversation with you unless he happens to be extremely shy, which you may be able to notice by his actions if he truly is.
You can ask him for help, give him a smile. Try to start small talk and say something like "how are you doing...I always seem to see you when I come here " You can ask his opinion on a product and ask if he has ever tried it. Little things will break the ice and then you can see where it goes from there.