Swelling is hard after ACL surgery?

so this tue. april 15th i had ACL surgery on my left knee. the doctor told me the surgery was a success and i should not put any pressure (walking) on it for a while. so thur. yesterday i accidently came up to quick from sitting down and i put alot of pressure on it to stand up. now today as i was putting on new bandages i noticed that the area where my knee and thigh meet is very swollen and really hard. not like muscle hard but in a weird way. its hard to explain but im just concerned if i should call my doctor or not or if im overreactng. so anybody with any similar or acl surgery expericence please tell me what the heck is wrong.