Union does not recognize their numbers. Get with your Stewart, and file a grievance or two. They're structures for warning letters, beginning with verbal warnings. Suspensions are a few steps into the process. Regardless, if you called when you found out you won't make it, because of a ups store hold up that would have otherwise had you back before 8 then you followed directive.
I've never heard of being written up for going over 9.5. I have heard of, getting fired for "stealing time" but that's a lengthy process that usually requires more than just one day being late and is very hard to prove considering the union doesn't recognize their numbers.
Sounds like your mgmt started something and it's up to you to protect yourself. Get with your Stewart and discuss a plan of action. If your Stewart is useless, call your union hall or speak to your business agent for your local. Goodluck, and don't let this stress you out. It's what they want to make you work in an unsafe manner to reach numbers that are virtually impossible.