A method includes, in a processor, receiving signals from (i) a first position sensor disposed on a shaft of a catheter, and (ii) a second position sensor disposed on a distal end of a sheath of the catheter. Based on the signals received from the first position sensor and the second position sensor, an event is detected in which an expandable distal-end assembly of the catheter is being withdrawn into the sheath while still at least partially expanded. A responsive action is initiated in response to detecting the event.