Pretty good chance that the boveda never really let the chemicals off gas properly. They are two way packs, absorbing when needed and providing when needed. So if at any point you were over the packs provided humidity level, it was probably absorbing the gasses you thought you were burping off, and then holding them within the jar the entire time.
The boveda’s are relatively newer thing, so not everyone has been exactly sure of best way to use them. I’ve been using them in my cigar humidor for a while, but I reserve them for storage purposes on weed. Only introducing them once I’m satisfied they are cured properly.
It’s not the only explanation, but probably most likely.