What's up with the supermarket employees?!

Customer service is basically a foreign concept in Kenya, so you learn pretty early on to lower your expectations. But the supermarket employees here have the strangest habit that I just don't understand:

I'll be going down the aisle slowly, looking for something on the shelves...or I'll be picking up a couple items comparing them, and a nearby employee will stop what he's doing and watch me or sometimes move closer to me. He won't ask if I have a question or need help, but he's basically hovering and watching me. It's really annoying and unnerving. Maybe they've been taught this in their customer service class...to be available for questions...but it ends up coming off like they need to keep an eye on me or I might steal something off the shelves. This happened to me four times today during my trip to the store, and I was about ready to scream. Instead I looked back at one of them until he turned away and moved along.