I have no evidence of Trickle Charging.
Share if you find any evidence of Trickle Charging.
In any case, folllowing those protocols, there is no possibility of a trickle charge: 
Do NOT charge LiIon unattended.
Do NOT charge LiIon overnight, unattended.
Do Disconnect the charging cable when the charge indicator says Charging has Stopped.
another example,
the charging chip on my PT-18, immediately after it turned green:

Battery is still connected to charging cable, the indicator light is green, and there is Zero Amps charge rate, but 4.99v:

4.15 volts from the fully charged battery, immediately after unplugging the charge cable

Charging cable disconnected from battery, Zero Amps charge rate, but now 5.03v:

As you suggested, the status LED seems to be using Volts to light the status light when the charge cable is plugged in… even though the charge status light is green, there are Zero Charging Amps indicated on the meter. I interpret that to mean that charging is switched OFF, and the Green Full Charge Status indicator light was being powered from the USB cable.