When you write a letter to a friend in German, you start it like this:
wie geht es dir? Wir haben uns lange nicht gesehen …
how are you? We didn't meet for a long time...
Here you could replace »lieb« by »geschätzt« (I guess its »valued« in English, but I'm not absolutely sure):
(ger) Geschätzter Hans,
(eng) Valued Hans,
But this is not the only possible usage of this word. When you welcome friends that come to your house to visit you, you might say:
Herzlich willkommen, meine lieben Gäste.
Herzlich willkommen, meine geschätzten Gäste.
Welcome, my dear guests.
Welcome, my valued guests.
This lieb in the meaning of geschätzt has nothing to do with the lieb that children use to describe lovely or cute things like fluffy animals with big eyes. The lieb that is used in greetings is used among adult friends as part of a welcome-phrase.
To welcome special guests, who usually don't follow every invitation, or who – when they come – come late because they have such a busy life, it is very common to say:
Oh, das freut mich, dass ihr doch noch gekommen seit. Je später der Abend, desto lieber die Gäste.
… desto geschätzter die Gäste.
Oh, I'm very pleased that you did come. The later the evening, the dearer the guests.
… the more valued the guests.
It might be possible, that the phrase »Je später der Abend, desto lieber die Gäste.« has not the same amount of commonness across the whole german speaking region. I have seen the movie »Der Untergang«, but I can't remember who said which sentence. I guess it was Hitler (played by the swiss actor Bruno Ganz) who said the lieber-quote.
As you know, Hitler was not born in Germany, but in Austria (in Braunau at the border to Germany, where his father had a job as a customs officer), and his ancestors lived near Zwettl in Lower Austria. Hitler himself spent the first 24 years of his life in Austria (19 years in different places in Upper Austria and 5 years in Vienna).
So maybe (I am not sure) you did hear a phrase, that Hitler learned in his young years, when he grew up in Austria, where this phrase is rather common.