A tool to list package deps sorted by buildtime?

[Michael Schwendt]

Scenario:

Assume I have package "foo". It's installed already, and the local RPM
database covers it and all its dependencies.

App "foo" used to run fine a month ago, but a rebuild no longer does.
Dependencies have been updated. Too many for "rpm -qa --last|less" or
yum's log to be helpful.

I'd like to run an RPM query on "foo" that displays the %{buildtime}
for all of foo's Requires, sorted by buildtime.

Does anyone know of an existing tool that can do exactly this already?
Or a script that achieves the same on top of an ordinary rpm --qf ... query?