FaceOfFear's journey

I recently found myself in a strange situation regarding a job offer at my current company. About two months ago, I interviewed for an internal promotion but was ultimately rejected. I was told I was the second choice and encouraged to look for similar roles. This was disappointing, especially since I received positive feedback from the panel after my interviews. However, just a few days ago, one of the hiring managers from that panel reached out to me with an unexpected offer for a different position on a new team they were forming. They mentioned that they had already spoken to my current boss about the move and just needed my approval to proceed. I was thrilled, especially since it came with a substantial raise. But then, I received an update that HR couldn't approve the offer letter until they posted the position internally for at least five days and interviewed other candidates. They assured me that this was just a formality and that I was still the chosen candidate. Despite their reassurances, I'm feeling nervous about the whole process. Is it common for companies to handle things this way? Should I be worried they might choose someone else after all this?