I have used Visa exemption/on arrival successfully for the past 8 years without any problems. But I am now retired and have been staying in Thailand far more recently with a view to moving to be with my girlfriend permanently. I think I have been put on notice purely because of the frequency and length of my visits. I think given that you have only been in the country for 50 days you should be OK. I cannot see Immigration refusing you at this stage (don't hold me to that! ) but if you are changing your pattern of stays I would perhaps be a bit cautious.
per 12 months...not necessarily year. I thought I would get away with 180+ days because of change of year. Nope. I was told 60 days only, no extension of 30 days leave the country for 60 days return on an DTV Visa, or similar.
My partners daughters boyfriend is an Immigration Officer. He has told me that it is now policy to flag multiple entries on exemption Visas and direct the visitor to alternatives. I have just been caught out on the same issue.
I think that that is standard. I pay in the UK £450+ for Travel Annual Insurance with ore-existing conditions, which only covers 60 days in each travel period. I have been told by AXA staff in Bangkok that for certain pre-existing conditions such as a previous Heart Attack Health Insurance, is impossible to find.