Parcel Posts On "Pinkish" Paper?

Is it normal for a parcel post stamp (any Scott Q1-Q12) to have pink paper? This is how it appears from a seller's online image. The pink-ness invades the unengraved portions of the stamp's upper half, but not so much on the lower half... and the degree of pink seems to vary with the permeability of the paper's composition.

This is completely normal. I assume you're showing us a mint stamp. For one, this can happen when the printing plate is not wiped properly/completely before printing; a mechanical process at this time, I believe. So there is a film of ink residue in the background. EDIT: see also Loupy's post below, the more likely reason based on the way it looks. That phenomenom is very typical of and visible on the US rotary press printings but this happens with flat plate printing going back to the earliest. US 1c 1851 issue stamps often have a bluish background cast for the same reason. And if there is a view of the back, then no such paper coloring appears there, except for maybe a few flecks in the expected ink color, correct?

Printed on a humid day with the paper holding moisture from the air, the ink will migrate across the face of the printing. This was done on purpose in some later printings and is known as wet print, where the moisture content of the paper was raised before printing. If you could look at the back of that stamp, it will be white.

This is especially visible on the Transportation Coils since they have so much white space

Peter

Yup, the stamp in question (a mint, gummed specimen) shows no discoloration on the reverse.

Thanks to all for the info