I've noticed two different instances recently in which the GENFIXes done by AWB have introduced line break errors.
The first was related to a transcluded section, where, it's necessary to have only a single line break afterwards, or else an extra space is created. AWB added an erroneous extra line break, creating a gap.
The second instance was caused by the existence of a hidden comment at the end of a section. Again, AWB created an extra line break (between the history and campus sections).
Given how widely GENFIXes are applied, any bugs it introduces seem cause for concern.