Strange how it is leaning to one side but otherwise looks just fine. I'd have thought that anything with enough force to push it over like that would have caused other more visible damage. Pretty grainy video though.
Whatever it was, it seems more likely that it was a booster issue than anything relating to the tower given that they were initially go for the catch. It was only during the boostback burn that they scrapped it.
The spacex website indicates that it was indeed an automated check of the tower that caused the catch to be scrapped.