Agree with the above. Theoretically possible as SSRIs (and fluoxetine in particular) interfere with platelet functioning, but if this effect was so pronounced as to actually be clinically relevant, I would have expected recurrent bleeding, not a single episode.
I've found in my patients with primary anxiety disorders, it can be quite difficult to get them on a medication that they are agreeable to taking regularly for exactly this reason. They seem to become quite preoccupied with side effects. I think I read somewhere that there is some evidence supporting the idea that patients with anxiety disorders are more likely to experience side effects from medical interventions compared to those without.
If this were my patient, I'd probably switch to a different medication because, after all, you have plenty of options. In my patients where this becomes a significant problem, though - i.e., we've tried numerous agents and all have been intolerable due to one side effect or another - I eventually have a candid discussion with them about this phenomenon.