That may just be a lymph node, in which case there is not really anything to worry about. I have had two inguinal hernia repairs and my lymph nodes there swell up periodically, especially when I have a cold etc. and can be quite sore. Those are solid lumps, the best way to find out is going to a doctor but my guess is that it is just that, during the op they sometimes sever the lymph canals and that can hinder lymph flow, therefore making the lymph nodes swell up.
You can try gently massaging upwards from your leg to your heart, that can help reduce the swelling.

thanks, that does make sense, and now that I think of it, that's what I think it is. It hasn't been bothering me, but next time I see a doctor, I will have them take a look just to be sure.