The owner said I was insubordinate because I asked the office mgr to change my paycheck stub hours to reflect what I was told by the owners in a meeting. I was a salaried employee with the standard 40 hrs on my stub. During the meeting the owners told me that I was only expected to work 30 hrs a week. I requested the change on my paystub to reflect that. Is that considered insubordination?

Depends on exactly how you phrased it.

If you were indeed salaried, it would seem that the number of hours shown on your pay stub would be immaterial.

But in any case, it doesn't matter if you were insubordinate or not, except perhaps with respect to determining your eligibiltiy for unemployment benefits.

There is no exact working definition of insubordination. Apparently you opened a can of worms. Might have something to do with benefits that don't apply under some hours per week, or hiring quotas, or a contract they have with the government - possibilities are endless. You were supposed to keep it to yourself and I am curious why you didn't. If others now know there may be an uproar going on.