Tracking down pesky PHP 5.3 errors
Assuming you do not have a debugger going (getting XDebug to run for your local development environment is probably the single most useful thing you can do the entire year), you could use debug_backtrace() at the place of the error (i.e. in the two form alter functions) to find out what is calling them. If you shoot its output into watchdog(), hopefully you can cross reference the time of the error with a particular invocation of these functions. Do be aware that these are form alter hooks, which get called for each and every form Drupal is building (and you might be surprised there can actually be several forms on a single page; just think of search and login forms). I.e. not every call will be the offending one.