Distance between plumbing vents and bath exhaust fan vents

[metolent]

Quick question about thru-the-roof vents.  I finally put all of my plumbing vents through the roof last weekend...  talk about scary.  So I'm about to take another (hopefully final) trip up there to install two bath exhaust fans through the roof.  However, one of them will be close to one of the plumbing vents (2" ABS). 

The question is:  How far away does the bath exhaust fan vent have to be from the plumbing vent in terms of horizontal distance on the roof?  For reference on this section of roof, the pitch is only 4/12.  Are there minimum distances between the plumbing vents and bath fan exhaust vents on the roof?  Are there similar minimum distances between bath fan exhaust vents on the roof?  Am I just being paranoid?   

Here are the references I've found, but these are for walls: 

http://sww-icc.org/Documents/2006%20Details/IRC-M1804.2.6-1(pg.1)_Vents.pdf
http://sww-icc.org/Documents/2006%20Details/IRC-M1804.2.6-2(pg.2)-Vents.pdf


I'm planning to call the inspector soon as well, but thought I'd ask here as well....

thanks,
matt