Agree, I have also never had this problem after 45 years making quilts! Opps, just tripped over my nose!!
You will see that we all experienced this, & there will be many suggestions offered.
I would starch & press the heck out of the area, if it still puckers, I have even used very lightweight fusible to hold it flat, than quilt the area heavy.
Good luck, hang in there, I'm sure you see it worse than it is, we are our worst critics, see everything.