I hear it all the time. People starting to share that they're not feeling so great, that they're struggling, having a hard time. And then - boom - they switch gears.
"But other people have it much worse, so I shouldn't complain."
If it's a therapy client of mine saying this, I'll often say something like, "This is your therapy hour. You get to complain all you want!"
I encourage my clients to complain, especially those for whom sharing their struggles doesn't come easy.