I don't get this never using soap thing
I admit I rarely ever use soap on Cast Iron normally, you don't need it and I'd never let it soak in soapy water
But I wont bat an eye to use it when I have deep fried 6 batches of fish and fries. Or worse yet, ever tried to clean soot of the bottom of a pot after cooking on an open fire. Try cleaning the bottom of a 15 gallon pot covered with soot with no soap.
a little tip.. I rub a lite layer of soap on the bottom side of my pot just before I cook over an open fire. It keeps the soot from sticking to the pot.
So that NEVER put soap on cast iron rule is BS.
I think it more a matter of the pot not being properly seasoned.
This is the best seasoning advice I have found..
Once a piece is fully cleaned and dried put it in the oven "naked"; no oil of any kind and heat it to 450°F. Leave it in long enough to just reach that temperature. Be careful and remove the piece from the oven and let it cool to where you can just handle it. This step works great for slightly darkening the peice and giving it a uniform appearance. No one likes a spotted or zebra stripped piece. Use Crisco shortening only and use a cotton rag (t-shirt) to apply a thin/very light coat on the entire piece. If there are tight nooks and crannies to fill in, use a Q-tip.
Once completely and lightly coated (note: we stress a LIGHT coat), put it back in the oven at 400°F for 30 (use a timer) minutes and at that point turn off the oven and leave it in the oven till it cools on it's own.
When you remove the piece it will have a nice dark brown uniform pantina that shines brightly.
You can repeat with one or more coats of Crisco, if you like, but you'll be happy none the less.