RF - changing a trace slightly from original design...?
My one concern was that the length of the transmission line from the chip to the antenna might be chosen to be some particular fraction of a wavelength for matching purposes. But the antenna datasheet shows high return loss at the operating frequency, indicating it simply appears as a 50 Ohm load at 2.4 GHz. 

Given that, either of your designs is likely to work. The initial design (90-degree bend) could be improved by leaving the antenna pad at a 45 degree angle to the "southwest" and then making another 45-degree bend when it meets up with the existing track.

The second design (part placed at 45 degrees) should also be fine, but might be harder to work with if you were doing a very space-constrained design.

Another option would be to keep the antenna oriented at 90 degrees but move it to the right or left a few mm so that a straight track from IC would run straight to the appropriate pin.