mare rearing

Question
I have had my Mare for a year now after getting her from a rescue.  She ended up in the wrong hands after being sold by a friend of a friend so I know her history: trained in dressage, western, housed usually at a barn (not pasture)papered paint.  When I got her from the rescue she had been bred and now has a yearling.  Over this past year I have weaned her from her babe, put her out in the pasture with a group of 5 horses (four geldings one other mare), then brought her back to her yearling in an acre stall/paddock.   

The two times she has reared were today, when she appeared to be in season, while on a kilometer track, on halter..appearing very "overly" alert during our walk, she suddenly sped up then reared.  The other time was when I was taking her from the pasture and the other horses while headed up a small hill, on halter, she whinnied then reared up.  Could her being in "season" cause this kind of excitement?  Since I've hardly ridden her, only been doing ground work with her, could it be a neck or back problem?  

This is my first horse and this behavior obviously concerns me.

Answer
Hi Jennifer.
  It's been my experience that a mare in season won't act up unless there's a stallion around.
Reading about her behavior, the first thing that came to my mind was that she was feeling her oats because she was again separated from her baby.
   If you want to keep her from coming into season, talk to your vet. There are several hormones that can be given.
   Best of luck!
Anne Stepien