Battery drain or not

Got a car where the customer has complained that the battery has gone flat twice since August. Did some simple checks, alternator output, digital battery test, live data said battery health was 75%. When I checked for a drain when the car goes to sleep I noticed the multimeter reading was changing so rapidly I couldn't read it. Next I put the graphing meter on it to try and read the current on a 1 second time base and could see the current is going from 0.03 to 0.12 amps very rapidly with a consistent waveform pattern. When I split the screen to display digital reading and graph the digital reading is 0.04. I guess this is the average draw? Does this count a draw then? Half of me says it is because the draw is going up to 0.12 but the other half says not because average is 0.04. What do you guys think?

Some vehicles go into sleep mode in stages and it can take 20 minutes or more a lot depends on the particular vehicle manufacturer. For example I found on BMW everything has has to be closed down and the keys removed well away from the ignition and door locks. What you are seeing looks like the alarm/immobiliser scanning the state of the locks.

Your graphing meter will be averaging the duty cycle of the 0.03a to 0.12a if it showing 0.040a that is aceptable in my book --- I work on 50 ma for a small car 80ma max for loaded luxury car.

As Andy says modern vehicles can take a long time to go to sleep. You also need to ask the customer about their driving habits - I live 5 minutes from work and in winter when it's dark and rainy (headlights, wipers, heater fan on) the battery slowly goes flat over a few weeks of 5 minute drives and I have to either go for a long "weekend drive" with it or charge it now and then.
Otherwise what I do with battery drain jobs is to connect a thin wire in series with the battery positive and scope the voltage drop across it. That way I can set it to a one hour time scale and check it occasionally to see what it is doing. I normally latch the doors while leaving them open so I don't wake anything up if I want to check something inside.
Also do a full system scan of all the modules - we had a VW draining the battery, everything worked perfectly but the radio had a communication issue and even though the display went off with ignition it couldn't receive its message to go to sleep - so it stayed awake and flattened the battery.

I say no draw. I'm with Andy - anything less than 50mA is acceptable in my book. Less than 20mA is ideal.

Like Desmond mentioned, I'd suspect this is more down to driving habits. Sounds like their leaving something on, or just not driving it enough.

GM's Passkey 3 systems recharge the transponder in the key when the key is inserted into the ignition. A key left in the ignition overnight can/will draw on a battery, too.

Then there are the intermittent faults.... like a slightly loose boot lid that occasionally keeps the boot light on.
I also heard of someone who had to resort to leaving an oscilloscope reading across a 1 ohm resistor overnight. They noticed that at midnight there was a 1 amp current draw, at 1 am it went away. The clock was drawing 1 amp for an hour each night which explained why they could never find a current drain during the day.