You need to get a Glock Armorer to look at it.
But if you don't want to/can't do that, you need to get this:
It will let you check where the cruciform/striker tail are meeting. You will be able to see it with this plate in place. If you have done a "trigger job" and changed this relationship to the point it is falling off during recoil, you can get into the condition you are speaking of. (It can also happen due to wear over time, and 16,000 rounds is quite a few)
Don't shoot it again until you get this checked out. If you don't have at least 66% or more of the cruciform on the striker, you need to get a new trigger or striker, or both.