I Hate It When this Happens!

So here's the deal; a year or two ago we picked up this Burke table & chair set at Hawthorne Vintage. The table has a tulip base and the four arm chairs have propeller bases. The cushions are original, but when you turn them over....

...you can see that the original color was orange. We've decided that we like the orange better so why not do what they did and respray them orange. Simple, right?
So with a can of Krylon orange spray paint for plastic in hand, I carefully applied a coat of paint.

I think they turned out pretty dang good. The color's almost an exact match of the original. I managed to avoid any drips or paint puddles. All that was left to do was let them dry overnight and as the Fonz would say, "Sit on it, Potsie."
Ahhhh..... we like this more than the blue.

Now here's where the "I hate it when this happens" thing comes into play. The paint just will not dry. It's tacky. It's been three days now and it's still tacky (tacky as in "Wow, that's sticky!" Not tacky as in "Ewww... that's tacky!"). See... a piece of newspaper stuck to it. YUCK!

Was it too cold? Maybe, but it was over 60º in the house. Was there an issue using plastic paint over the existing paint? Maybe, but I don't know about such things. I know it's not too thick as I was planning a second coat. I'm at a loss.

All I know is now I have to spend a few hours with the cushions and a can of paint thinner and a few hundred paper towels and take off the orange and hope they still look decent.

I hate it when this happens. :-(