Singlespeed & Fixed Gear - my fingers are numb

So, i rode CM tonight. Not my first time riding it, not my first time riding long distance BUT my first time doing so on my bike that i put narrow straight bars on last month. NOW, my left pinky and ring finger are, i'd say 85%, numb. The bike I normally take on long distance rides has bullhorns so I guess I'm not used to being limited in my hand placement options. I dunno. This ever happen to anyone else? After how long of numbness should I start to worry?

Get them amputated quick! Just kidding. Use them and the numbness will pass. You have pinched a nerve because those bars do not suit you at all. Ditch them soonest.

When your riding it helps to take you hands off the bars (one at a time) and shake them out. Could be that you have too much weight distributed to the front of the bike. That puts undue stress on the wrist joint which will restrict circulation to the digits, yo.

Higher stem, slide the seat back and or vary hand positions.

I can second that. Aside from the bars no doubt sucking, they probably are also putting you in an inappropriate position. You should be able to comfortably sit without supporting yourself on your hands. Although there a lot of ways to figure out this fit, I think it might help just to do a quick check where you don't change your body position but remove your hands from the bars. If this seems really awkward and unbalanced, you probably have a bad fit and are relying on support from your hands too much. Oh, and get some gloves.

Yeah I had the exact same problem a number of years ago with my old mountain bike. All I had to do was either lower my seat, or raise my bars (new stem). The position the setup had put me in was not letting the blood get to my fingers well. I tried gloves first, which helped a bit, but I would still get numb after a little while.
I haven't had that problem in years now.