My thoughts as well,but why no warning lights and OK after the motorway blast and fine today.(If you know hwat I mean).
That's due to the fault priority signalling method (ooeerrrr !)
The ECU evaluates general engine health in terms of completed drive cycles. When you first start the car one of the things which is tested, via a monitoring system and fault checking, is the EGR valve.
It can take a couple of minutes for enough different operating conditions to have been created for the EGR health to be properly checked. If it is established there is a fault a temporary fault flag is set.
For the EGR faults in particular it takes three temporary fault flags to be set before the warning light comes on.
If you have two EGR fault flags and then a completely good drive cycle takes place, the fault code/engine warnign light is delayed. After several fault free drives the temporary faults are removed from the log completely
This is why if you block the EGR valve completley that by your thrid drive cycle you should get an EML light on. But then if you remove the plate the light will put itself out eventually when enough good drive cycles have been completed again and then the fault is automatically deleted.
In your case a fault definitely occured and the ECU logged it, but not wanting to panic you (!) it made a temporary note of it (and created some special data called 'freeze frame' data)
but then after a good run the condition of the EGR improved as a result of the drive (Assuming the fault was the EGR in the first place) and the ECU relegated the fault stored in memory because it could have just been a small hiccup.
In the case of a blanked EGR, when i put a full blanking plate on the EML light comes on during the thrid drive cycle, then if I take the plate out the EML light goes out after something like 5 - 10 drive cycles and is deleted from the usual fault registers
There is a permanent fault log in cars made since about MY2008 which will still show that an EGR fault occured, called the 'history log' but then after 40 good drive cycles even those faults get deleted too. (This is known as 'mode 10' or 'mode $0A' data)
Finally, the only reason I know all of this, is because I was also curious to know why I didn't always get an EML for an obvious fault too !