Not strange actually. Instead an indication the glow plugs may have been intermittently coming on causing all your apparent other problems. The dash glow plug light would not reflect that event.

I would run a wire from one glow plug to a light in the cabin for the next while to indicate when they are on. Otherwise you might start chasing your tail again or burn out the latest plugs as well.

Or perhaps the many cycles back to back when testing earlier might have done it. Either way I would run the wire and light just in case. This would either indicate the problem or clear the possibility of it.

Get your old plugs from the shop and test them for continuity if you can.