Question is about the Pittsburgh Maulers cap. When I was signing players this afternoon, I had them up against the cap. The sim ran, nobody rejected my offers, and now they have over $4.5 million of cap room. I guess they do have room to sign that 4th year OL after all.

Where did the extra room come from? Might it have to do with them only having 48 players under contract before the sim ran?

Here is my guess.
When you re-signed those guys, it figured their bonus for this season as part of the total bonus for the new contract. Because of being in Week 12, the reworked bonus for this season would be significantly smaller than the original bonus.
Just a guess.