Definitely possible. I don't know that the portal change is related to WL movement. In the last 5+ years, there was no mention of the portal change signifying the first WL decisions were coming. Over the last 5+ years (except last year's COVID cycle, which was released on March 25th), the first WL batch was always sent at the end of February and no later than March 5th.
Pitt on average has 2-3 WL batches with past years going as high as 4 and as low as 1 (last year).
As others mentioned Pitt over-enrolled last year so they could just be waiting on more data before deciding how large their WL movement will be for this year. It could also just be that they are running behind and they will release them this week, but that would definitely be an anomaly.