Wyeast 2007 (Lager) and white layer on top of beer?

Hey...real quick!
I'm fermenting a light lager beer at 50 degrees.
All is going well, gravity went from OG 1.043 to 1.006 in one week. (I pitched 2 packs of Wyeast Pilsner 2007 w/ starter and it fermented nicely.)

I checked the gravity today and got 1.006. I noticed a thick white film on the top of the beer. I stuck in my "turkey baster" (after being sanitized) to get my sample wort. The beer tasted good and for a light lager (my first attempt) I was shocked at how good it tasted. I need to do a diacetyl rest from what I've read, but I don't know how soon to do that. I figured two weeks...but the beer has fermented better than expected and I don't want the yeast to peter out too soon before I warm it for the D-rest for about 48 hours.

Question: is the thick, white layer of foam MOLD? or yeast residue?
And should I do the diacetyl rest NOW or wait a couple more days? I will eventually rack and lager for about a month before bottling.

I worry about the thick film on top of the beer...but it tastes good and no bad smell or anything. I just don't want a problem if I can catch it prior to being a "mold" problem.

Thanks for any tips!

Bob

probably not mold. I hear mold is actually hard to grow in beer. it could be some other undesirable growth, but if it tastes good, I'd suspect it is just some yeast and krausen. if it is down that far in gravity, I'd think you could do the d-rest now, then rack and lager it.

I hope that yeast is a good one, I'm about to use it for the first time.

This is my first attempt at a lager.
I wanted something my dad would like, and for that...I needed to keep it like BUD/MILLER (etc...) I just used 7 lbs. of Pilsner and .5 lb rice solids.

It's got a nice malty taste and the 1 oz. of Hallertau hops blended right into the background. (keeping it about 18 IBU's)

Anyway, I can't normally do LAGERS in NC, without the aid of cold weather and my garage getting to 50 degrees. (and we've had snow and ice lately, so that helps) I keep my 5 gallon fermenting bucket in a larger bucket of water and add ice if needed. The water surrounding the fermenting bucket keeps the temperature fairly stable even on the days it got to 55-60 degrees outside. (My fermentation has been at 50-54 degrees for the entire week!)

I only made a 4 gallon batch, so maybe it is finishing up?
I want to make sure I get the diacetyl rest before the yeast are ready to "hang it up" and start LAGERING! So I will probably move it into my basement finished room and let it warm up to 62-64 degrees. (for approx. 48 hours.) Then I'll cold crash it.

I was worried about it being mold, since LAGER YEAST seems to be bottom fermenting. But maybe it's just some "beer junk"?? I know the beer underneath is clear, tastes good and has no bad smell. I've ordered more ingredients to re-use this yeast as soon as I'm ready to harvest some of it after the racking to the secondary. Thanks for the help! Hopefully the remainder of the process is un-eventful and all goes well. I've never had any mold issues and I am pretty determined to keep all my stuff (equipment) clean.