Has anyone had a thyroidectomy and then become overactive/hyperthyroid again!?
If you had a partial thyroidectomy, I could see where that would be possible, especially if you had an autoimmune disease such as Graves as the reason for your hyperthyroidism in the first place.
If you had a total thyroidectomy, the only reason you would be hyper again would be because your thyroid hormone replacement therapy dosage is too high and needs to be adjusted.