No! It's not your fault at all. Taking a bird from a flock to being a bird on its own is stressful in the same way finding yourself alone on a desert island is stressful - but this stress would only highlight a disease. Your bird was asymptomatic, so I still don't think it sounds like a disease. Take care of Jedi - if Jedi was bonded to Megatron, he/she will need extra TLC while the pecking order reestablishes itself.
It's not at all crazy how they impact you. I think to devalue them is the crazy thing. It's a reminder of how precious life is, even in the smallest places there are unique and wonderful experiences that await you if you take the time to connect, give respect and pay enough attention.
I think Megatron is simply perching forever inside your heart now instead of on your shoulder.