I'm making an IPA and I'm going to be dry hopping it this weekend in the secondary fermentation phase. I've been thinking about the dry hopping process alot, mainly about the diffusion of the hoppiness throughout the beer during this phase. I plan on putting the pellets in a nylon sachet to keep them contained for easy removal, but by doing this is it possible that the beer immediately surrounding the sachet will be more hopped than the rest of it?
And should I stir it lightly in order to make sure there is more even hopping?
Also, how can I be sure the dry hopping won't contaminate my beer?