I purchased a pair of Florsheim shell cordovan longwings on eBay recently, and have just started to wear them out. They had little-to-no-wear on them when I purchased them. It looked as though someone had worn them once or twice at the most. I've worn them out twice now, and I've noticed there is a spot on them that is already cracking right around the crease on the left shoe. When I first noticed I wasn't sure if it was cracking so I put some Saphir Renovateur on the shoe and then waited a week and wore them again. It's definitely continuing to crack. Is this a common issue with vintage shell shoes? Is there anything I can do at this point to moisturize the shoe or decrease the potential future drying/cracking?