Should I be concerned?

I have a clutch of four eggs (Lesser X Spider) and this is my first ever clutch. They're in the incubator at 89 degrees and when I candled them yesterday, at day 43, I still see red veins but I don't see any snake. I do see what seems to be yolk at the bottom (shadow). I thought by now, I'd see a snake moving or at least the egg is almost at its capacity?

Pretty much what I've been seeing since about day 40. I believe the shadowing at the bottom to be the hatchling, having seen movement. My first clutch is on day 53 now and the shadowed area is gradually becoming more pronounced. (I'd love to see candling pics for people around the same stage.)

I'm only speaking from my own very limited experience, but it sounds like you have nothing to worry about...

Just maintain the proper heat and humidity, the rest is in the hands of nature

Don't worry :) as long as they are candling good, you should be fine!

Can you elaborate on "candling good" because this is my first clutch. I do see red veins. Is that the only thing I should be concerned about? Other than temp and humidity.

Yes, red veins are what you are looking for. Candle again in a week and you should see some movement. They might have just been sitting still when you candled. They don't move constantly so sometimes you might miss it ;)

Ok, thanks for your input guys. *crossing fingers* :)