My cat did this after I moved out of my parent's house for about six months and took her with me. Was with two guy roommmates and BF at the time. She wasn't comfortable with the new place, and had separation anxiety. She'd meow loudly and try to crawl under the door. Got to the point where I'd just leave the door open a crack until she came running, then I'd let her in there with me and close it fully for privacy.
Always very clingy, but not too obnoxious about it, thankfully. She learned quickly to lay on my lap instead of the computer keyboard.