Under cutting?

[VrefA]

a good question for those much more senior than I (Rookie here).

2 man crew:

A1 attempts and misses lay-up. B1 trips over own feet and falls to the left of the paint. A2 jumps, obtains rebound, lands, and then jumps to attempt shot. A2 drifts away from the shot and lands on B1, who is still laying in the same position from when she fell.

My call: No foul. B1 was in that position before A2 jumped to put the shot back.

Any other opinions/advice?