It seems like you have had a series of coincidences.
Though it may feel strange to keep bumping into him at different stores, it is still possible to have this experience.
Being that you like him, it can be easy to read too much into everything.
If you keep going to these stores at times that he would be free, there is a good chance that you will bump into him.He is a store clerk. Hence, it is the more likely that he would visit other stores.
You just so happen to bump into him a few times being that you work as an Instacart employee.
Try not to read too much into the fact that you have bumped into him a few times at stores.
You can try starting up a conversation with him and see how he responds. Doing this will give you a much better idea as to whether this guy truly likes you or not.