Not sure about your case, but I my knee felt loose after surgery and I was told that it was because I'd lost so much quad muscle. Im working on getting it back, which is taking ages, Im only at about 17 weeks post ACL reco I think (im loosing count a bit now!!) and at times I still feel that my knee is loose, and find myself wondering if it hsa worked even though my OS is really happy with it at the moment. I think that so early after your reco you are probably going through what I have..... talk to your OS if you are really worried
Alla