Exhaust Film

[knk]

Since a recent service and lots of miles in the hot, dry weather I have noticed a dry, grey powdery film over the rear of my Griffiths. I assume it is from the exhaust.
Seems to be running fine and is at 55k, 30 of which I have done in the years I have had it.
I have never noticed this before. Should I be concerned? Cat breaking up?

[Wildfire]

Do a search, there was a HUGE post about this a while ago.

[knk]

Thanks. I had already tried to search the forums as I thought I remembered similar. No luck.

Can anyone provide a link?