Just got my second Surefire L4 in today and noticed a green tint vs my first one which produces bright white light.  Both lights are the L4-HA-WH models.  Anyone else notice a difference in the light produced by LED's or have a similar issue?  Is this normal?  I also have a couple X200A but they both produce bright white light with a slight blue tint...  Thanks for any insight!

It's the Luxeon lottery.

LED's are rated for wattage, flux or lumens, color tint and forward voltage {Vf}.
It's called the bin code. A typical Luxeon bin code will look something like this... RV1KW
The bin code can be found on the back of the star, (the part the actual LED is glued to).
Disassembly (sometimes major) of the light is usually required for this. Proceed at your own risk.

The (R) is the flux or lumens rating.
The (V1) is the color tint.
The (K) is the forward voltage(Vf).
The (W) is the LED color.
These rating are not totally specific, they are a range.

A 1 watt (R) binned Luxeon LED will have a flux or lumens rating between 39.8 and 51.7 lumens.
The forward voltage {Vf} is also a range, the (K) {VF} stated above will have a forward voltage of between 3.51 and 3.75 volts.
A white (W) rated LED can have a color tint ranging from purple, blue, green, red or yellow.

BIN CODES EXPLAINED

The flux and Vf can be found in the first couple charts at the top of the page.
For the color tint, (V1) in this case, scroll down the page till you hit the first colored chart (New Bin Coding System) and you'll see that is leaning towards the yellow and green portion of the spectrum. Meaning it can range from green to yellow, or any where in between.

When a company buys lots of LED's they usually request a specific flux rating and VF, (both important for output and battery considerations), but sometimes they just have to play the hand they are dealt as far as color tints goes. Remember a white (W) LED can fall anywhere on the color spectrum chart and still be rated a white LED.
XO and WO tints tend to look the purest white, but I prefer the V1 rated ones, the yellow tint being a little easier on my eyes.

Thanks BF and thezman!  Thezman that hurt my head  and No, will not be proceding at my own risk and this point in time  Interesting to see the way it all falls into place though as there is a range that they can play with and call it all the same  Thanks again for the knowledge you all bestowed upon my little pea brain

Yeah, it hurts my head too....

I had no one to explain it to me, and it took weeks to figure out on my own.

Once you start working with LED's and start swapping them out for different tints, it all becomes a little easier to understand.