I was very excited for the release of the St Croix GXR Bass Systems Combos, specifically the frogging casting one. When browsing recently I noticed that there was no left side retrieve for the casting set. Does anyone know if there will be a left retrieve option or if there is one already out?

Just buy a quality reel and a quality rod individually.  Combos are almost always a rip off. 

Doesn't look like they have any left handed options on their site or on Tackle Warehouse. Given that I'd say no but if it means a lot to you I'd send them a message through their contact form on their website. That way they would at least know there's some interest in left handed combos. You could also just build a combo yourself. In this case the rod uses the SCII blank so that would be something like the Bass X or Premier...and for the reel the Lew's LFS was going for around $50 recently if you can still get one at that price that's probably what I'd do and then wait for a good sale on rods (eg. the 20% off at Tackle Warehouse sale right now for mailing list members) and you should have a very similar setup and probably save a few bucks.