The packages build successfully after this message but do i have to worry about this?
Probably. It is a shared library and so it relies on the "provides" to tell apt/synaptic when to select it as a dependency. If the spec file has no explicit "Provides:" tag then this failure will render the library useless as it won't provide anything. Worse still, if it were to be put the repo like this then anything that depends on libboost would be removed when users update.
You can check the final RPM with:
rpm -qp --provides <packagename>.rpm
to see if it actually providing anything.
I would need the SRPM (or at least the build log) to be able to tell why it is failing.