If that was how the two ends of the pushrod were fastened together, it was only a matter of time before they slid apart. There's a huge amount of stress on the pushrod, even on small models, and the pushrod needs to be securely fastened by mechanical means. CA does not adhere to metal very well; a slight shock load would pop it loose.

Is that how the instructions told you to install the pushrod?

Pushrods for short runs are generally one piece of steel, with a Z-bend at the servo end and a threaded-on clevis at the other. Longer runs have a few alternatives:
1. Nyrod/Goldenrod - a flexible pushrod material that is run through a well-supported tube. The tube must be supported at regular intervals or the pushrod will just flex when force is applied in the "push" direction.
2. A steel pushrod in a well-supported tube.
3. A spruce, fiberglass, or carbon fiber pushrod, with short lengths of steel pushrod securely fastened to the ends.