Marina's blindness- as a new character, she was always blind
Jenna's bedwetting- secret, then disappears
Buster's asthma- discovered, then disappears
Binky's allergy to peanuts-discovered, then disappears
Nobody develops a life-changing problem. And the episode tonight Operation DW, who figured that if any character had one it'd be her? I did. Season ten is largely DW's season.