Here's a weird situation.
I have just edited an answer of mine over at English.SE in order to improve it. About three and seven seconds later, I got two upvotes for that answer. Now, obviously, those people who upvoted it weren't looking at the edited answer; they had loaded the page before I submitted my edit, so they were looking at the original version. They cast their votes for something that was greatly different from what there actually was at that time.
Consequently, my question is: are their votes now locked? Does the SE engine just look at the timestamp of an upvote, or does it leave some room for reading the answers, by looking at the timestamp of when a visitor loaded the page before casting his vote(s)?
You could say that in this particular case it doesn't matter, because I have actually improved my answer (well, I hope you would say that). However, I could have just as well replaced it with "OMG unicorns are so gr8, if your not unicorn u suck!!!1!11!!" or something to that extent.