YES! It happens on various browsers (Pretty much other than IE) and Mac and Windows alike. I think I know how to get it to work though - try it:

When the popup comes up, you have to change either or both fields. You can "change" into the same information - but it looks like until you type something into the fields, the script does not believe you have updated the date.

It (the script) probably does not realize the fields are non-blank and is expecting an input, even if the info is already there.

This has worked for me on the firs try.

Let me know how it works for ya!