Was cutting a 3/16" wide dado in a piece of Lyptus using an Amana
upcut spiral bit. Was cutting 3/16 deep in half inch stock. Router
is a Porter-Cable 7518 in a lift.

The bit came through 1/2" stock during the a 3/16" dado and you never felt
or heard a difference as the bit was rising ??

This has happened to me before, but I can usually feel/hear the difference
as the router starts working harder.

Glad you are ok.