If the owner said all the horses were acting goofy then I wouldn't worry too much about it. I have days when all of my horses are acting weird, usually when the weather is fixing to change or there is a full moon.
It was really windy and I had not rode her in 10 days. That bug still making it's way thru the horses though so I'm just keeping an eye on her. Did you see that I found a daddy? I'm gonna breed her in Feb.