Checking my plumbing - single sink to double sink

[Awake]

After some helpful advice here, I have completed my rough plumbing to convert a single-sink vanity to a double-sink vanity. Here is the before:

And here is the after:

Question: When I was putting in the transition fittings to go from the ABS to the PVC, I found that the upper (vent) piece would move a bit up and down. That was very helpful in getting everything into place, but it made me nervous about what is happening on the roof -- do I need to go up there and check to be sure a vent cap has not gotten pushed out of position?

Does anyone see anything else I need to fix before closing this back up?

 

[hj]

The pipe slid through the opening, and usually there is nothing to worry about, since it apparently has not leaked previously.

 

[Sponsor]

 

[Awake]

Thanks!

 

[Smooky]

If there is a problem where the vent pipe exits the roof, a perma-boot is an easy way to fix the problem.
http://www.permabootstore.com/?gclid=CInTktCThcACFeRj7AodQFUAXg
http://www.homedepot.com/s/Perma-Boot?NCNI-5

 

[Reach4]

I think he was referring to something to support the vertical weight from the pipe.