I'm not sure how easy this would be to implement, but I imagine it wouldn't be hard. Anyways, I was thinking, wouldn't it make sense if the 'Quick Reply' option was only available on the last page of the thread?
I suggest this for two reasons:
1. To prevent people who did not realise there is more then one page of posts from replying.
2. If they want to ask a question about someone's post, which is on the first page, they post a quick reply on the first page, but on the second page someone has already asked it and they didn't see.
Hmmm...I couldn't really explain my 2nd point well, hope you understood it. :)