You or a mod may have briefly accidentally locked then opened it back up. Clicking the Moderator Tools in the upper right above the first post is where you go to lock/open threads.
Also, while there is no rule against it, PayPal Friends & Family is quite frowned upon by many here. It offers no protection to you or the buyer should something negative happen. It also cheats PayPal out of the tiny fees that they earned by you utilizing their service, fees which you agreed upon when signing up.
That is a good way to lose sales as many will see F&F and hit the back button, regardless of what is for sale.