Any issues with including a return label/package using Priority Mail?

I purchased two Priority Envelopes on the 10th. I was shipping something to a friend and they're shipping me something back so I wanted to include another priority envelope and return label so they could just put it in the mailbox/drop off box. I got everything done, paid for both and left the office.

My tracking shows that USPS was in possession of the item on the 10th around the time I purchased them then 3 hours later that it left the facility. I didn't mail my package though until the 12th and just put it in my buildings outgoing mail for pickup.

Will this cause any problems with either package? Could either of them be returned to the originators address since the dates aren't lining up with supposed possession vs actual possession?? Any issues with tracking? Right now they both just show in transit to the next facility.

Is there a better way to do what Im wanting? Trying to make it as simple as possible on my friend.