What format camera was this taken with? (was it 35 mm, med format/120, or something else)?

Additionally there is an effect called "drydown" on a black and white print. The print darkens and dulls when it dries from what we perceive when the print is wet.

I believe that Les Mclean still has an article posted in the articles section that describe an excellent way to determine for yourself how to test and compensate for the effects of this on your paper.

Good luck.