I'd call your order in and make sure it has the spring; the spring is a must in my "stuck button" opinion.
It is a must. Apparently, Rob thought it was enough of an issue too; so he added the spring. The button stuck on one of mine a couple times, and I called Rob immediately. I didn't use either of mine again until he new buttons arrived, and I installed them. No more problem. There is a charge for the button/spring assembly. If I recall, they were $15 each.