Turn Signal outage?

The other day I was driving home and got the rapid flash on my left turn signal, so I figured I had a blown bulb. Got home, checked it and yes, front left not working. went inside ordered new bulbs. Next day I go out and now the turn signals all work. Any Ideas?

I have after market headlights (which use the factory socket and bulb) and I did some wiring at the left rear for canopy and backup camera. None of those operations used the turn signal wires. It hasn't happened since.

 

I have had this issue on and off. Mine is the pins in the harness right at the light. Mine are currently working after playing with the wires but I have not found a permanent fix.

 

I've had instances where the bulb stops working, then you hit a bump and the filaments make contact again and work for sometimes days or sometimes months.