Cormyr Hitching Post thinks my horse is not a horse?

[Xotaes]

Outside the Bubbling Bulwark at the Customs Post:

Code: Select all

<100%hp 62m 100%mv> 
l
The High Road
 N-The High Road   E-Darkness        S-The High Road   W-The Bubbling Bu
The hard-packed road thins here with the intrusion of a tall
half-timber inn with a ponderously leaning second story held
up by the efforts of a number of regularly-spaced jetties. A
slanting, tiled roof casts a shadow upon the road rivaled by
only the garrison's stone tower.  A gaily painted sign hangs
over the door, swinging upon an iron arm and waving to group
of colorful pennants posted around a weathered stockade that
stands opposite the inn across the road. 
The sky is cloudless and warm and a cool northern breeze blows.
     A few hitching posts. (perfect)
A black and chestnut painted horse stands here.
A cat is here.

<100%hp 62m 100%mv> 
hitch horse
A Purple Dragon approaches...
The Purple Dragon shakes his head at you.  "Goodman, get this beast from here.  This is for horses."

If my horse is not a horse, then what is it? Did I accidentally buy a doppelganger or a polymorphed chicken?

[Talos]

Amended, pending update.