The rep system is competitive. It could mean other people are gaining faster than you and pushed you down.

It could mean you got flagged.

OR like me

There is a glitch.

I actually moved to 67 last week and after chatting with a dev it's decided to be a glitch. There are APPS to verify glitches on the Steemit interface.

Woo Hoo 67 but Boo Hoo it doesn't show. lol

www.steemstats.com
www.steemdb.com

Are good ones to start with, you can type in anyone's name and see all their and your own activity and that jazz.

And

www.steem.cool
But it is also glitchy at the moment