2 days after my gastric sleeve surgery I gained 10lbs. The nurses said it was from all the IV fluids they pumped into me. Is this normal? Did it fail?

Water weight. It is likely as the nurses said, that your weight gain is related to the Iv fluids you received. Time will tell as you should lose that weight over a 5-10 period after surgery.
Be patient. You would not expect any weight loss from the operation in this short period of time. In fact, it's likely that the weight gain was from the operation and surrounding needs. It may take a few weeks to start realizing weight loss from this surgery, but after that point your weight loss should be more regular and predictable. Be patient.