not obstruction
 

There are parts of plays which have a similar effect as obstruction, but are not because the fielder has the ball.
An example:
Runner slides into a base and partly past it with one leg, but still on the base.
The fielder, trying to tag the runner ends up under the extended leg and the leverage lifts the runner off the base with the gloved hand holding the ball.
Not a deliberate push, just momentum.

Not out, not obstruction, just a safe call.
And continue watching, of course.

Any comments, or rules I don't know about.