I'm not having any problems and I've "Thanked" a lot of people this morning.
When i push the "Thanks" button, it shows it been pressed but after i recheck it's been undo, is this related to recent glitches or it's just me ?
It's not as much a glitch as an idiosyncrasy. The "thanks" button (like the "edit" button) is a toggle. Hit it once and it says one thing; hit it a second time and it reverses it.
There's a similar problem with comments. If they're a bit slow posting and you hit the "post" button again to hurry it along, it will post twice.
That happens sometimes Matt. I would log out and clear your history and cache and then log back in and I bet it will be fine then. I've seen that with the Votes and Thanks sometimes and that's what I do to remedy it. I've seen some Thanks from you this morning just fine. All seems to be working well on the site.