Should I have used a primer on before painting vinyl shutters?

I recently took down my exterior window shutters, washed them, and then gave them a fresh coat on paint. They look great and I have put them back up on the house. I started thinking I probably should have primed them first. Do you think the paint will ';stick'; to the surface or will I end up having to redo them sometime on the near future?Should I have used a primer on before painting vinyl shutters?
If they've been painted before you should be ok. If they've never been painted, even if you use exterior paint, you might have a problem with the paint not wanting to stick to the vinyl.Should I have used a primer on before painting vinyl shutters?
If they were already painted, then they were probably primed when they were manufactured. If you used the right kind of paint for exterior vinyl, they should be OK, time will tell.