Is it bad to route a trace edge of a rectangular pad?
Keep in mind that the solder mask will be expanded by some mils (the exact number depending on the manufacturing process you're designing for) around the pad so you'll get an asymmetric pad shape that will tend to pull the package. Probably not a big deal, but it also looks ugly. If you had a bunch heading off in the same direction (or, worse, antisymmetric on top and bottom rows) it might become an issue- symptom would be a rotation of the package during the soldering process. 

The same trace seems to bend unnecessarily close to the left pad and is at an angle close to horizontal but not quite- try to maximize clearances and keep almost-horizontal traces horizontal. A 45 degree snap on angles works well for most purposes.