If it didn't seal in 14 hours at room temp but did in the fridge it's a weak seal. Keep it in the fridge or freeze it - it's not worth opening up/going bad on the shelf.

Agree.

For future searches that might bring up this post--the same goes for jars that "seal" (depress and stay down) when you're just checking the seal more than a couple hours later. I had one of a relish that did that, I was just poking to check, and one hadn't popped, but stayed down after I pushed on it. It was the next morning, so in the fridge it went.

Also, for freezing, you do need to pop whatever seal is there, let it freeze, then can tighten up again. Otherwise, the jar could possibly break due to freezing expansion.

It might be prudent to also pop the seal if it does seal in the fridge since there are some strains of botulism that can survive refrigerator temperatures (38 degrees and higher). But all of them require a low-oxygen environment, so popping that (weak) seal is just a little extra insurance if you're putting something in the fridge that was underprocessed or under-acidified (I'm assuming the OP's salsa was from a tested recipe so the other jars are fine for shelf storage, just adding info here for future searches).