Not normal at all. The transfer port inside is clogged with grease more than likely. Its not a vacuum but the negative side of the air chamber is now pressurized with probably 80-100psi if I had to guess.
This is a really bad situation as you need to get the air out of the negative chamber, but you don't have any shaft to clamp on to remove the foot nut. I would take it a suspension shop if you have one, purely for the safety aspect.