Stupid first question you'll get from support: Are you sure you have a horse?
This has never come up for me as an issue, could it be really bad lag? or is everything else normal? I remember during beta there was like 30 seconds lag sometimes in pvp and the more actions you pressed the worse you made it.
Actually its a guildmate of mine. He was riding his horse Sunday, but then Monday at login he could not call his horse. Tried going to the stables and buying a new horse...nothing. Tried going from Glenumbra to Behtnik and nothing.
Will try the /stuck tonight...thanks for the suggestion.