Yep, happened with my dc when he was 10 months old. Obvious tooth coming through, little white nub, told the whole family (in the way you do with a first baby!) and then two days later it totally disappeared. This coincided with him jumping in his cot and occasionally hitting the bars so I was terrified that he’d knocked it out. Never got to the bottom of it as about a week later out it popped again and did no further disappearing acts.
Just one in a long line of parenting moments that sent me to google..I seem to remember reading it happens alot.