Originally Posted by
Bob'sYourUncle
There is - all passengers arriving from outside the EU and continuing on another flight must be screened (EU-mandated).
If for some reason UA does not interline your bags, then you will have to claim in them in T2, clear customs, then walk them across the plaza to T1. Note that the Christmas market is going on on the plaza, but early in the morning most stands will still be shut.
You are right. Last time I connected in MUC (and took the bus airside from T2 to T1), it was a Schengen - Schengen flight, so there would have been no need to reclear security. However, I did experience the reclearing earlier this year in AMS. Good catch.