We do not mention Not To Current Standard issues on warning notices anymore, but we are allowed to do so on invoices/job sheets etc. I always do, simply because the next guy may say "did the last guy not notice....", effectively undermining me. So, generally, nothing to worry about.
Is there a lot of white showing outside on the flue?
However. inadequate support of flues IS an issue and is classed as "At Risk", so he should have rectified or invoked our process.
It is mentioned as AR in 5.3 and 5.9 of the Unsafe Procedure:
Microsoft Word - IGEM-G-11 Ed 2 Gas industry unsafe situations procedure - FINAL FOR PRINTv3