You had a really long surgery and it was 4 hours long, meaning you got put under heavy anaesthesia. When you woke up you had been talking about your girlfriend about how amazing she is to the nurse looking after you the entire time. When your girlfriend walks in, the nurse chuckles, walking over to her and explaining what you've been saying and how the surgery went saying to your girlfriend "She's been talking about you since she woke up" before walking out.