During the course of my meditations, I have begun to ponder what exactly 'wrong concentration' means, particularly, during meditation I find there is a very fine line between concentrations that lead to a sense of understanding and being present and aware, and those that leave me feeling disassociated and distant. Doing a bit of Googling, I came across this article, and found it very relevant, I thought I would share it, if I am allowed to.http://www.accesstoinsight.org/lib/auth ... mbers.html
Once your mind was firmly established in a state of concentration, Ajaan Fuang would recommend "lifting" it from its object, but not so far that the concentration was destroyed. From that perspective, you could evaluate what levels of stress were still present in the concentration and let them go.
Tsongkhapa recommends this too