157dB

It could be moisture.
Did you change the bulbs during a very humid time?
Turn them on and let the housings heat up.
The moisture (if that is what it is) should dissipate.

If it does not, it is some contaminate on the reflector.
Did you handle the bulbs with your bear hands?
Sometimes oils from the skin will transfer to the
glass portion of the bulb and cause hot spots
and off gassing that could collect on a cooler
surface such as your reflector. This will happen
quite quick as the bulb heats up for the first time
and the reflector is relatively cool.

ebritt

I was very careful not to touch the bulbs, the film almost looked like smoke from a burnt wire. It has since disappeared. Maybe some moisture just got in during install.

Art161

Glad the problem went away. Another thing to consider when doing an install is to leave each old bulb installed until you are ready to install the new bulb. Don't remove all four old bulbs before you start installing the new bulbs. You don't want to give dust, dirt, moisture, etc. an opportunity to get into the assembly. I don't know how you did the install, so can't say whether that could have been a contributing factor. The old sealed beam headlights didn't have that problem.