Clone under 250w HPS, Yellow tips, Help!

So I have a grow journal going in the 'Indoor growing' section of rollitup.

So the clone is still under the 250w HPS about 2 and half feet away from bulb to top of plant. The temp is staying at 79-80 and the humidity is 55%.
The only problem is that as the new nodes are growing in, ! I'm seeing yellow spots on the tips of the Nodes that grew in YESTERDAY, today another set is growing in ! I'm confused as to why these yellow spots are occurring? I'm not talking about the large visible yellow on the large leaves(That's the result from the light burn when it was too close), Its yellow on the smaller nodes that are about an inch long, It's kinda hard to see with a cell phone pic but theres small yellow on the tips and a small dot on those leaves. Anyone have any thoughts?

*I've circled in red where the yellowing is occuring*

Thanks all

any expertise advice?

bumpppppppppppp

Damn, how long did it take for them to look like that?
Are you foilar feeding them with the lights on?
Are you using and have been using nutes?

I've yet to use nutes but I'm starting today. The major parts of yellow in the pic are light burn from about a week ago, I'm more concerned about the smaller yellow spots on the new leaves. I'm keeping the light on 24/7 and I got the clone about a week ago.