Priming sugar doesn't even fully carb in one week. You definitely have 5 volumes of CO2, which has not fully carbonated, it has just carbonated a significant enough fraction to lead you to believe it's done. I had a honey cider that I intended to be a still cider. It was a still cider even after two weeks in the bottle. After a month there was a few bubbles. Then after 6 weeks they were so carbonated you'd have thought it was intentional. This is after 4 weeks in a primary at controlled temps. It ferment s out so slowly that my SG readings couldn't pick it up over 3 days.
The only reason you don't have over carbonated beer or bottle bombs is because you didn't let conditioning finish. That was super lucky. Glad it turned out.