reftex-cache-cite-echo

reftex-cache-cite-echo is a variable defined in `reftex-vars.el'.
Its value is

t

Documentation:
Non-nil means, echoed information for cite macros is cached.
The information displayed in the echo area for cite macros is
cached and even saved along with the parsing information. The
cache survives document scans. In order to clear it, use M-x
reftex-reset-mode .

You can customize this variable.