What irritated and concerned Peter about the samples Dan sent him?

The samples Dan sent to Peter weren't properly packaged.

"What annoyed him was the fact that the bits of meat were wrapped in aluminum foil, like pieces of leftover hot dog. The hot-dog-like meat was monkey spleen, and the ice around it was tinged with red and had begun to melt and drip. The samples also included the tube containing the throat wash and some blood serum from the monkey."

Peter reprimanded Dan in the following way.

"Let me tell you how to send a sample to us. People around here may be slightly paranoid, but they get a little upset when you send a sample and it drips on the carpet."