REFER line 123 of class.admin.autocomplete.php which is start of cleaning the cache.
"clean_page_cache" has been deprecated (as of WP3.4) and is replaced by "clean_post_cache".
I made a simple edit on line 125 to make the substitution. If you prefer you could delete the entire if..else.. statement and just insert a clean_post_cache command.
PS: FWIW, I'm in the process of upgrading my site from WP2.5.1 to WP3.5. I was using an older version of Simple Tags (I was quite happy with) and I've upgraded to the latest version of Simple Tags because of an incompatability. At this stage (19 Jan 2013), the plugin seems to be working as advertised.