Second Sweat

[Maliblond@aol.com]

I have a question that I hope someone can answer for me.  A horse that I ride
has been getting a second sweat on his hind end within a couple of hours after
a training ride. After he is cleaned up I put him away, when I return later to
feed he will have sweaty spots on his butt.  The sweat is not always in the
same place on his hind end, sometimes it is high up on his butt and sometimes
it is down on the sides.  He isn't sweaty or hot anywhere else.  He has never
tied up before and I don't think this is tie-up because he doesn't show any
other signs, there is no discomfort and he moves fine.  He is fed half alfalfa
and half multigrain hay twice a day, and he doesn't get any grain or hot feed.
I am wondering what is causing this second sweat and if it is anything I
should be greatly concerned over.