Behavior of the LED pin of the BQ24400 in trickle charge mode

We are using the BQ24400 part in order to charge NiMH batteries. We set the fast charge mode to last for 8 hours by the component used. We expect the chip to go into trickle charge mode after fast charge mode. Thus we believe the charging should be complete after 16 hours. We are watching the MOD, LED and RC pins in order to determine the mode the chip is in when we come back the next morning. We observe RC is at 2 V, MOD pulses every second and the LED output is high impedance and pulled up most of the time which would indicate the chip is still in trickle charge mode. However, after the LED pin being in high impedance for 10 seconds, the LED pin will go to 0 V for 200 ms and then go to 2.5 V for 2 seconds and then back to the high impedance state. 18 seconds later the LED pin once again goes to 0 V for 200 ms and then to 2.5 V for 2 seconds and then back to the high impedance state. Then the pattern repeats itself. Is this normal behavior in trickle charge mode for the BQ24400? If the chip were in trickle charge mode we expected for the LED pin to be in a high impedance state until trickle charge mode ended. After the weekend we expected that the chip would be in the charge complete state by this time with the LED pin in high impedance, the RC pin having a saw tooth waveform and the MOD pin periodically pulsing. With the LED pin acting the way I described along with the state of the MOD and RC pins, what state id the chip in?