I got home today, and I always go over and say 'hello' to my furbabies

and I noticed Harley, my youngest Budgie - was half asleep, but then woke up and started 'yawning' although it turned into more of a gagging...
I was really worried

so I came on here and googled some info and I found that if a bird is opening his mouth, like gagging, that he's just adjusting his crop, and it's totally normal?
Is this true??
IMG_1484.jpg