The fact that she was paying more attention to the area (itching perhaps) would be a good indicator that it is bothering her in some fashion.
With any new lump, growth, boil, cyst, bump, etc.....especially on a Boxer it is better to have it checked out and diagnosed sooner rather than later.
If it is nothing you can ease up on worrying. If it is something you can have it addressed before it gets worse and possibly more bothersome for her.