It does not look infected yet. I zoomed in which gives a pretty good look.
I would soak it with a damp, warm cloth and then see if you can slowly clean it up a bit soaking more as needed. Feel the incision area and see if it feels warmer than other spots in that area.
After you get it cleaned up, watch it closely for excessive reddening, or oozing. Keep feeling the area every 5 or 6 hours and if it is noticeably warmer, red or oozing--check with the vet.
__________________ Mario  was adopted May 2015. Now he is a service dog and brother to Bailey the Airdale mix |