Germany has its own customs rules...
I'm still sure your parcel is just slow.
It's always the same around the holiday time - most packages arrive fast and only take 1-2 weeks - but you have always those who take 4,5,6 weeks and longer...anyway if you sent around the holidays or not.
Just to show you an example - when I was at the post office today I received 4 parcels and 2 letter sfrom the US.
1 parcel was stamped 23rd Nov. 2012
1 parcel was stamped 31st Dec. 2012
1 parcel was stamped 5th Jan. 2013
1 parcel was stamped 7th Jan. 2013
And the letters had were stamped on 13rd Dec. and 5th Jan.
You see - you can't tell exactly how long it can take.
And when you've sent 4 weeks ago it's still in time and it can still show up every day.
I guess it hasn't to do with the german customs at all.
It's just the float of parcels they receive over the holidays - and they often need weeks to work that all out.
I'll def. keep you updated!!
My next run to the post office will be tuesday.