If they were not taken care of then they could take longer to get up to the magic weight to breed. I would keep them on a size appropriate weekly rat regiment. Because there is no way to gauge how quick a snake will grow in weight the only thing you can do is a good feeding schedule and hope for the best. I used to breed caramels and i found with the animals i was working with they were slow growing animals. Could be something with caramels i dont know. Or could have just been the ones i was working with. Im sure some guys have caramels that pound and look like dumb trucks but for me i didnt have luck with them putting weight on fast