When casinos start slow paying it usually only means one thing in my eyes, bolt before you get any further issues and take your money elsewhere. So many casinos slowly fold without informing the customers then suddenly drop the bomb shell. Don't wait for it and get out now.
Not saying this is the case here, just wouldn't risk it.
100% agree would not trust a casino if they do not even give you a reason as to why the payout process is taking longer than expected.