This disrupts Rubio's narrative of the party "coalescing" around him, especially if Trump starts to pluck off some of the Christie endorsing governors like LePage, Hogan, etc and a few congress critters.
Unfortunately, Baker will never endorse TRUMP. I hope the Tea Party primaries him in 2018.
He is super-tight with Christie and Scott Brown, and is very hard-line on immigration for a moderate New England Republican. But yeah I don't see him endorsing TRUMP. He probably will stay neutral though now.