Nikon FM2n shot at wrong speed?

I set the shutter speed to 1/2 and instead it just shot at around 1/125 or above from the sound of it. Is there anything wrong with it and could too much desiccant dry up the lubricant? And if so how do i restore it back?

Added (1). Oh i forgot to mention that it shot at faster speeds every 1 out of 5-10 shots.

Dry lube would make the shutter even slower, not faster

Finish the roll of film and then with the camera back open, shoot at 1 second all the way up to 1/1000th second.

If you are not sure of the shutter being able to give you the correct shutter speeds, take it into a camera repair shop and have them do a test of the shutter speeds and list what they actually are.

This should cost less than $25 and you will know precisely what each shutter speed is.