Why does the paper make Han’s suspicious?

Hans is suspicious because the Nazi Party didn't initially want him.

“The Nazi Party?” Rosa asked. “I thought they didn’t want you.”
“They didn’t.”
Papa sat down and read the letter again.
He was not being put on trial for treason or for helping Jews or anything of the sort. Hans Hubermann was being rewarded, at least as far as some people were concerned. How could this be possible?
“There has to be more.”
There was.