Ask your grandparents your questions while they can still answer. That window doesn’t announce when it’s closing.

There is no notification for the end of a conversation you could have had. The questions you are saving for a better moment depend on somebody being well enough and present enough to answer them, and that condition holds right up until it does not. None of that is a reason for dread. It is a reason to ask sooner rather than later.

Write down three questions you would regret never asking, and ask one of them on your next visit. Keep it light if light suits you both: a story, a job, how they met. No explanation of your sudden curiosity is required.