In the program I'm working in, a PDF form is used as a template to generate reports. Once we're done filling in all the information using ABCPDF, the PDF is flattened and then attached to an email. When the final form of the PDF is opened in Adobe Reader, everything looks fine. Then, when Reader is closed, it asks if you'd like to save the changes you've made.
Why does this happen when no changes have been made since opening the file in Reader? My one guess is that it assumes a form with filled-in fields has changes in it.