I don't think too far forward would cause a saddle sore alone unless you are constantly pushing yourself back.
Try another saddle. If you have a grippy one, try one more slippery. Or if you have a slippery saddle, try one with more grip. Sizing and shape of the saddle could also be an issue.
Location of the sore would give you the most information. Probably TMI for this thread, but a fitter could help and loan you some saddles also. In any case, I would swap out saddles and see if anything changes.