My chickens do the same thing to me if I go out in sandals. I've never really thought much about it. But, now that you got me thinking, my guess is that they are just curious. Chickens seem to be on an all day quest to find good things to eat. I always try to bring some kind of treat when I go to collect eggs, and I'm the one that refills the feeder, so I'm pretty sure that my chickens think of me as The Food Lady.
I'll put this on our Facebook page and see if anyone else has an idea about this.