Thanks for the reply. A couple questions:
First, to clarify, are you saying this IS a potential problem? I can't believe I'm the only website owner who has this setup. And I don't see why an F5 refresh creates problems -- that would re-generate the script w/correct settings; at worst, the same issue as before recurs -- it doesn't change anything.
By putting the code in separate files, do you mean have the PHP script generate a separate .js file for each user and link each user's click event to a unique file? Seems like that creates a LOT of server files.
Can't comment on your dynamic script element -- that's out of my league; need something simpler.
If this is definitely an issue (i.e. the browser does NOT cache all external script files for use on future click events), please confirm -- I may end up dumping the external files altogether and just print the js to the page.