My minpin was Microchipped on tuesday now a lrge lump,HELP

[user3773]

hi, i had my 20 pound minpin vaccinated and microchipped on tuesday and today, saturday, he has a rather large lump in the area, about the size of a walnut.I assumed he may have some swelling, but i figured it would be immediately after the insertion, not 4 days after!! Is this normal..
he doesnt seen to be bothered by it but it bothers me, hubby says i always overreact.. He wants to wait and see, but im worried of the what will happens if it get worse.. Vets office is closed now and not open tomorrow, sunday, so i was hoping that someone could tell me if its ok to
"wait and see" or if immediate actions needs to be taken, thanks