He is totally clear of the shed now - damp facecloth and a good excuse to get him out for cuddles
We have also found the issue - stupid tho it is!! A piece of substrate had gotten into the door runner - the doors are 3foot tall glass so pretty large in terms of viavrium height - and even tho the doors were closed and no risk of snakey escaping the piece of substrate was leaving a slight gap at the edge of the door. This obviously increases airflow and reduces humidity = bad shed!! We tend to check the humidity when we spray and it was getting up to 85% with no issue and the lowest it was getting was 55% which is its normal low end. The problem was it was drying out much quicker than it should.
When i found the "fault" i did a test to check, normally it takes 10 hours to drop from 85% to 50% which is when we respray - with the door gap it took 1.5 hours!! So for 8 hours each day and each night his humidity was too low.
Guess we got complacent once the system we use was working for a period of months with no issues - we WILL be checking it more often now!!!
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May you have more good days than bad

You never know how strong you are - until being strong is your only choice
There are no dark clouds - just well hidden silver linings!!