Thanks for you replies sunny and zab,
Yes, sunny, I know now that was a mistake of mine leaving the colt right there outside the round pen. Usually I'll have them to where she may see them but not interact. I really think this was a freak thing and she'll be fine, cause she has been just super so far w. Everything else.
Zab, leading her with a rider on is what I did the first time she had a rider on, that worked well. I think she'll be OK, I know there is always a chance that she'll get frisky or what not. I always lunge first and get her to listen to me. Thanks guys, for your advise