What kind/brand of resin are you using? Some resins, even when fully cured, are softer than others.
Sometimes resin can take longer to cure if your room settings arent ideal (i.e. too cool or too humid) which may explain why your resin needed an additional day.
Ive started my first jewerlly project using epoxy resin. The instruction say the curing takes 24hrs but the rings still felt a bit tacky so I left them for 48hr. They have now hardened and no longer feel tacky but if I put pressure on the sides of the ring there is a slight bit of flexibility, should this be the case? This is my first time working with resin so not quite sure when to admit defeat on this batch and start the next! Thanks