Lumber Split in Roof Rafter
Yes, checking is common and doesn't usually compromise the strength of a board. That crack appears new due to the bright color of the newly-exposed wood. However, I see no reason for concern, especially considering the robust solid wood deck you have, which effectively spreads load to adjacent rafters.  

Now, any "professional" who laughs at your questions shouldn't be called upon again. You don't know whether other issues you may raise will also be dismissed with such rudeness. They also should not have been dropping bundles on your roof if only as a measure of respect. It certainly is unpleasant, and it dislodges dust and can crack drywall or plaster.