Glow Plugs fail for a number of reasons;
- too much current (from a power panel),
- old age,
- factory defect (poor production run),
- external contamination.

If you are getting a flight out of them, you didn't cook them with the power panel.
Old age is out.
Bad batch - is possible (but unlikely) - try again...

Contamination, can be from the way that you handle them on installation, to the way that you transport them in your flight box to (worst case) metal fragments in the engine...[X(] [:@]

You can solve the first two contamination problems by being vigilant.
Metal fragments in a new engine - can be disasterous! [:'(]

I would start by flushing the engine out with fresh fuel and examining the piston head through the glow plug hole, you can look at the piston side from the exhaust port. If there is any scraping you will see some evidence.

Depending on what you see, ... either take the engine to a dealer for a second opinion or go flying! - (The flushing could have removed all of the debris.)

Good Luck!