My headlamp melted while using the original bulbs! I?d been running the engine in my garage for 10 minutes or so when I noticed what I thought was condensation in the centre of the large headlamp lens.
Running my finger over this ?condensation? showed that the lens had crazed and bubbled up!
Luckily my dealer changed the complete lamp without quibble under warranty.
When I run the engine now for more than a few minutes I drape a wet cloth over the lens.....just in case.