I have a feeling this is some anti union move, given it's happening during negotiations with the Teamsters. Perhaps it's a smaller increase than what the union members want, meant to weaken their resolve?
Yep. Most companies are being huge fucks about labor relations; bigger than they've been in quite a while. The post-WWII "gentlemen's agreement" between labor and capital (as pathetic as it was) has been completely abandoned. They're back on some gilded age bullshit... sounds likely we're gonna have to do a general strike.
If you read the actual article, there are two things that stand out:
The changes apply to employees at non-union locations.
and
Other benefits for non-union workers include an additional week of vacation after 30 years of employment and vacation for new employees during their first year.
So from my understanding you may very well be correct, instead of trying to block unions through negative reinforcement, they try to block them by rewarding you for not joining one.