She was in with a stud for 4 days last June and she was covered when I picked her up. The stallions owner said the was breeding her for 1/2 the day before I picked her up. She was in heat.
My Mini Ellie Mae does that sometimes too, backing into me when I enter her stall while she is eating. I have done the same by sending her out of the stall and waiting to let her back in for a few. She has been doing it less. Eventually I am hoping it will stop.