No increase in dust was observed by LDEX, no change was seen by UVS, no propulsion products were measured by NMS. Evidently, the normal native lunar atmospheric species seen by UVS and NMS were unaffected as well. It is actually an important and useful result for LADEE not to have detected the descent and landing. It indicates that exhaust products from a large robotic lander do not overwhelm the native lunar exosphere.
LADEE Project Scientist Update: Intial Observations of Chang’e 3 Landing | NASA