I have found that after adding ground pepper (any type, color, or heat level), some dishes seem to be saltier. This sometimes occurs with other spices, as well. Note that I am not using anything else that contains salt.
I always taste as I go and something will seem to have the perfect amount of salt. But almost immediately after adding pepper or other spices the dish will seem to be too salty.
Also, I have cooked something that seemed to be perfectly seasoned, but if one adds ground pepper at the table, it seems to be saltier.
Another example is that when I cook certain types of curries and use a wide range of other spices, a minimal amount of salt is needed, and the dishes do not lack any salt flavor.
I have learned over time that when other spices are to be added to decrease the amount of salt, so it's not an issue. (I can always add more, if needed.) However I am curious as to why/how this happens.