I was denied a jumpseat on UA 5623 from GDL to IAH this morning (Sep 27) by the captain.

I fully understand that the JS is entirely at captains discretion but I have never been arbitrarily denied it's use. Over the years I have carried hundreds of jumpseaters and have never denied anybody. I understand that there may be an operational reason why I couldn't be accommodated but, if so, I wasn't informed of the reason.

I'm a mainline UAL captain and would hate to have to start denying Skywest pilots the use of my jumpseat.

Thoughts?