let me try to explain
you built your city, it tripped the goody hut , so the random number generator rolled to see what you'd get, the value is deciphered to be "heal unit", however, its a city, it can't be healed, so it rolls again, your bad luck, its free experience, again a city can't get experience. after 10 tries of rolling, these 2 items or others that cannot be applied to a city are what the random number generator keeps picking, it decides there must not be anything you can have, and quits, rather than rolling forever.
Obviously there were things you could use, but your bad luck, the random number generator never hit those options within its 10 tries. its a fluke.
if your second came on turn 3 or 4, i'm guessing it wasn't city expansion but a warrior or scout, well your unfortunate luck, all ten tries of the random number generator must have come up with something like "heal unit", which you likely couldn't use because your warrior at that point should still have full health. after 10 tries it gave up again
again, its not that there wasn't something from the hut you could use, its just that the number generator kept picking things from the list that you couldn't use. That is what i believe he is saying happened, it should be an incredible fluke that it happened twice, much less so quickly. it's a fluke coupled with really bad game design.(you think they'd just cycle the list and pick the first thing you could use rather than quit, and at the very least give you a message that the hut was abandoned or something.)