It could be that your body is fighting off an infection. The only way to really know is to get a biopsy. Your doctor may want to watch the lymph node to see if it grows any more. The biopsy won't hurt but it'll give you peace of mind.

I've had 2 lymph nodes removed that came back benign. They've grown a little in a year and half and am now scheduled for another biopsy. Good luck.