Should I be concerned and what should I do??
it appears to be scar tissue, however, hard to tell unless its examined in person. The good news is that you are only 3 weeks from surgery, so areas are still healing and improving. I suggest you follow up with you surgeon to evaluate and treat this further.
Thank you for the photos. I agree with the others that this is not a common issue. In my experience, these lumps are frequently either a small fluid collection or a solidified hematoma (blood or bruising). If so, this can be drained with a needle. Regardless, you should see your surgeon for a follow up visit. Take care and best of luck.