Newbie here - I just up-potted these clippings about two weeks ago from plastic cups and I'm noticing that some of the leaves have yellowish spotting, while others are solid green.  (all have new leaf growth since up-potting). 

I'm in NJ and am keeping them by a window indoors.  I have a heating pad underneath set to 78F and when the sun goes down I turn on the T5 light about 2-3 inches overhead.  

Watered every other day the first week of up-potting, now just once a week.  

I will say that when the top leaves were new in the cups they were light green, never got totally dark.

Any idea what's happening to the leaves?  

     
The first picture is the one in question for me as I don't know if that' the natural greening/darkening process, or if something else.  In the second picture the leaf was once dark now has yellow spots.   The third is a different cutting and looks normal (to me). 

Any help is much appreciated. 

Do you have it in a fast drying soil. The soil look to be peat moss. How was thing going when you were watering more often.

nothing a light dose of liquid fertilizer can't fix...just be careful with the dose.

Aaron4USA, how much fertilizer should I use, and how often?   I have Aqua Vega A+B, but haven't used since they were in plastic cups. 

Should I water, then add liquid fertilizer, or just the fertilizer?    

Fig_Pig66 - the soil is an organic mix I found at Home Depot, for two of the pots.   The other one is miracle grow.   

I can't say for sure, but it sounds like you might have a DIF problem.  Plants are sensitive to their environment.  Days typically are warmer and brighter than nights.  If the day - night temperatures are equal there are consequences.  Internode distance is decreased - this is used by commercial growers to regulate plant height.  But as you can see under "Drawbacks" chlorosis (leaf yellowing) can occur.  http://en.wikipedia.org/wiki/DIF_(technique)   If night temperatures are higher than the day temps, plants could actually decline to the point of dying.  78 degrees seems high - 70 is more usual.  But whatever temp you choose, try dropping it at night.  Are you turning the light out at night at all?

As Aaron4USA mentioned, please be careful with fertilizer on newly rooted figs.  Not overwatering is good.

These figs look OK to me. 
Did you use the same soil mix for the fig in the last photo. 
The right soil mix and the right balance of water and nutrients go a long way.  You look like you are progressing well.

I do turn the light off at night.  However, I don't think that would contribute to the problem that much since it is a fluorescent light and produces very little heat.

But I like your idea of dropping the temp on the heating mat during the night.  The temperature range throughout a 24hr period is pretty high, as I've noticed from the soil thermometer that during the day, in direct sunlight, the temps can get up to 86+ degrees.  
How much fertilizer would you recommend for the half gallon pots they are in, and how often?

Pino,

Good observation.  The last pic (healthy one) I used nothing but peat moss since it was in a plastic cup. Now it's in normal potting soil.   

The ones that are yellowish were in just perlite (with a little vermiculite) during the plastic cup phase, about 3 months.  

Maybe now that they are in soil they will do better?

I think so. 
The better the soil mix the less soil deficiency symptoms some of which sometimes look like disease symptoms.

I always use a weak fert on young trees, just so they have access to some nutrients.  Very weak, 10:1 whatever the directions say.  I make a gallon full strength(e.g Aqua Vega A&B 8ml each), then dilute 10:1 when I water.  It seems to work well keeping the young trees healthy without excessive growth.