Lactose film

I have a beer (braggot) in primary that has a high percentage of lactose in it. It has developed a white film on the top of the beer after about 4 weeks. I don't think it's an infection at all, it looks a lot like cream floating on the top.

Has anyone experienced this when using lactose?

Details:
1 gallon batch
4 oz of lactose
1 pound malted oats
1 pound honey
Oats were mashed and sparged, then the lactose and honey were added to the 100 degree wort.

No temperature control on the fermentation.

was there no boil? sounds like an infection from your details

dcp27 said:

was there no boil? sounds like an infection from your details

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Yep. Sounds like an infection. Lactose is a sugar, and dissolves just fine in liquid.

There was a boil.
I hope it's not an infection.
I'll have to taste it and see what I have.

I'll post a picture too if I get the chance.