In my experience, most shops collect oil in a large drum. The tech pulls the drain plug and walks away. They don't measure what comes out.

I'd take the above advice and read the dipstick at every fill up (as a good habit).

With no obvious leaks, you might want to replace the PCV valve. I'd say inspect it but its a cheap part and if you take the time to inspect it, may as well just replace it.

You may want to have a used oil analysis done on the next couple changes as well.