A binary program compiled against ncurses 4.2 on RedHat 6.1 and run on RedHat 6.2 which uses ncurses 5.0 but which has the shared library misnamed as ncurses.so.4.0 can segv due to ABI changes in the library which mean that version 4.2 and version 5.0 are not binary compatible as is incorrectly stated in the changelog given in the spec file from the source package. The problem is the definition of the TERMTYPE structure, and in particular the Strings member which is now a pointer to an array of strings instead of being an array of strings. Hence referencing a member of that structure (such as acs_chars) in a binary built against the old library and run against the new one will fail. Note that http://www.gnu.org/software/ncurses/ncurses.html states quite clearly that the major version number was changed because of changes which invalidated existing shared libraries.
This will be fixed in 7.0. The change affects only one function that isn't being used frequently (it's used nowhere in the distribution, powertools and contrib/net), so it's not necessary to release update packages for 6.2.