it sure sounds like that, but no.
USCIS does not wait for the I-140 to clear before issuing receipt notices.
If you have gottent the receipt notice for I-140, the I-485 should follow. .The RD for both applications, filed concurrently, at the same time, will be the same. At least they 'should' be the same.
It does appear that they receipting process is taking longer than any of us would like, but you will surely get it sooner than later. If you think about it, between July 2, and July 17, there were hardly any applications, so you should not have to wait too long given that people who submitted July 2/3 are starting to see receipt notices.
Again, it depends on whether your case gets transferred between the service centers, which may add a couple of weeks extra.