hard lump/knot on incision

Heather
I'm 10 days PP- I've healed very fast and been pretty active..walking the whole time, going up and down stairs at home, bending down etc. I haven't done any lifting or anything that's on restriction though and about 2 days ago I got a lump on the left end of my incision. It's about an inch long and half an inch tall. It's gotten harder and feels very sensitive to touch. It's not warm and no puss. Normal? Anyone else with similar experience? Thanks!