Yes, I was surprised too. I lived in MUC for 18 months and was always impressed by the airport on my numerous visits.
My travelling has normally meant that I do not transit (it is one of the advantages of living near to LHR!) but I had fully expected transit passengers to be screened at the gate or sent to the regular x-ray channels and the carry-on to be marked as having been re-checked.
When I was not re-screened on my my outbound journey, it reminded that - unless I much mistake - the bomb for PA 103 was loaded at an intermediate stop.