just spayed my pup

 Sheila, sometimes swelling can occur on an  incision after surgery.  It may be fluid or a bit of tissue coming out between the first layer of sutures.  In any case, it is best to have the vet take a quick peek at it to make sure it is healing properly.  They usually do not charge for this.  

To minimize any chance of post surgery problems it is really important to make sure a puppy is kept  quiet (as best you can), outside on a leash to go to the bathroom only, no running, jumping, rough housing or stairs for at least 7 days.  Good luck!