Mine tend to check in with me like this all the time on walks, sometimes I just acknowledge them with a 'good boy/girl, go on' (which is their release command) as being acknowledged and released again is reward enough in itself for them and sometimes I'll ask them to do something like heel for a minute or so or I'll send them out in a specific direction. Personally I wouldn't give her food for coming back as she's only coming back for the food, as you say, she's expecting it, she's not coming back to check in with you or to see if there is anything else you want her to do but it depends on how you see these things I suppose, I know for a lot of folk the main thing is that the dog comes back regardless of their motivation.