We talked about this already, and I think it's a good idea.  But I just wanted to call attention to it for everyone else.  Basically, if the ICRF->Fixed transformation is not available (because the data is missing or even just not downloaded yet), we fall back on using the TEME->Pseudo Fixed transformation.  If we don't do a good job of prefetching the ICRF data (which we're probably not, currently), this could result in an (imperceptible?) jump in the Sun and Moon position.