When I picked up my pup after being spayed, was told they saw a hernia in the recovery room above her incision, this was not apparent when she was prepped for surgery or on the surgery table, so how did this happen?

This isn't the forum to get medical advice for your pet, any answer would just be speculative at best.

I can't give medical advice, but if the vet's practice didn't call while your pup was still sedated, I'd ask why and what are their communications during surgical visits. After hearing that answer, you may decide to schedule a get-to-know-you visit at another vet.

Whenever my pet is sedated (by a truly outstanding vet):

• they tell me what to expect and I sign pre-authorization prior to arrival
• confirm a phone number where they can share status updates at arrival
• call me, sometimes more than once if scope of work changes based on new information, such as from x-ray to verbally review alternatives and allow me to decide how to proceed (take care of just what planned, or more found) and again after monitoring to give me all clear (pet doing well in recovery, ready to pick up)
• review everything when I arrive to pick up, tell me what's expected, any instructions, and answer my ?s

Basically, if it was my puppy, I would've wanted to know of additional findings (in this case a hernia) while pup was sedated and have an opportunity to decide to have them perform that operation too while pup was sedated 1 time.

Not a medical professional for dogs. But get your dog checked out immediately at a different place. You can do it. A hernia is not a joke and after make sure your dog does not do any heavy stuff after, fiber and hydration. I spoke to a few vets out of curiosity. This is so even if your dog has weaker muscles it is less likely to happen. Hernias are caused by pushing through the muscle wall that are weak in dogs. Having the digestion be less strenuous and no lifting and pulling will help.

Once again, I am no medical professional for dogs. Find a place to get your pup checked out too.