Team Builder Queue Discrepancy (and question)

I noticed something strange last night. I wanted to play something different than my usual Akali mid and felt like playing a mage mid that was not Ahri.

So I go through the process of selecting my champion (Morgana), choose mid, choose mage (which has the star next to it), and then Team Builder tells me my wait will be "Very Long." I only ever see that really if I am picking something strange. Morgana is a mage and declaring her as such shouldn't trigger the long wait.

So after five minutes I give up, and go back to champ select.

I once again pick Morgana, same result. I switch to Lux and it changes to "Short". Same position. Same "Mage Primary/Support Secondary". Same "Star on the Mage choice". I switch back to Morgana and get "Very Long." I switch back to Lux and get "Short." I ended up playing Lux after a minute or so wait.

How does this happen? I know declaring a champ as something they aren't (like say Akali as a Tank) will often give you this result. However, Morgana is a mage. I do not think it is the MMR adjustment for new role/champ as I only had 2 games as a mage, both on Lux. Both Morgana and Lux were eligible for the adjustment.

Thanks in advance for any insight anyone has into this.