I have just received the "niederlassungserlaubnis". But with very strange conditions.

I have passed 3 years working with blue card in Germany with A2 language certificate.

The problem is I have received a green paper with the "niederlassungserlaubnis" which says "Erlischt bei Inanspruchnahme von sozialleistungen" which translates to "expires when social benefits are used".

Is that legal? All my friends didn't have similar paper. And what I knew that by having the "niederlassungserlaubnis", you have the right of all "sozialleistungen". Any one know what should I do? What does the law says about that?

One more strange point, the new card has an entry "Karte Gültig bis" "card expired in" and is written the expiry date of my passport. When I checked with others, their card has the entry "Gültig bis" "valid to" and written "unbefristet" = "permanent". May be because the addition of word card? Is that normal also? What should I do here as well?

Help!