Swollen Lymph Nodes Immediately After Surgery Are Normal?

I've had a BIRADS4 lesion (5mm) showed on MRI, was told ir was not aggressive (type 2 curve) and probably benign. 3 weeks later I've had nipple-sparing mastectomy with immediate reconstruction (12 days ago). Today I notice a swollen node in my right armpit, ~1cm, soft, rubbery, painless. I noticed 1 in my left armpit too, more mobile. Is it normal to have swollen nodes in the armpit after this surgery? Or can this be caused by the 5mm non-aggressive lesion that I had, if that were cancer?