One off vomit- truly sick or not?

I went in the get my 16 month old out of bed this morning and realized he had thrown up at some point overnight. It wasn’t completely dry or anything but it wasn’t warm like he had just thrown up either. I got him cleaned up and he was begging for food so I let him eat a banana, knowing it might come back up. He devoured the banana and hasn’t thrown up since and is acting fine.

Last night I was out during dinner time and my husband fed both kids the rest of the fruit that was about to go bad. Could a strawberry that maybe should’ve been tossed instead of eaten cause a one off puke like this?

He did have a bit of a runny nose (common for him) so I was thinking maybe post nasal drip gagged him too.

We are supposed to see the grandparents later today and I’m wondering if it truly could be just a one off puke and not a true sickness? Obviously if it happens again I will brace for what will run through our home but I kinda feel it’s not really sickness. Am I delusional?