I have noticed that using php's error_reporting function at runtime seems to cause it to report notices that have occurred previously.
What you said is just regular behaviour at must related to parts of your code which you havn't posted. Check my example. It will call a non static method statically what will cause a E_STRICT message:
Class A {
public function notStatic() {}
}
$a = new A();
error_reporting(~E_ALL);
$a::notStatic(); // ... silence
error_reporting(E_ALL);
$a::notStatic(); // Strict standards: Non-static method A::notStatic() should not be called statically in