I believe it was Korn that first had me worried about this. And - don't get me wrong - am still worried but slightly relieved at the same time. I did a littel research, and if the source is correct it's certainly good news:

Sodium stearoyl lactate (and the similar calcium stearoyl lactate) is made by combining lactic acid and stearic acid, and then reacting the result with sodium hydroxide or calcium hydroxide to make the sodium or calcium salt. It is used as an emulsifier in processed foods.

Replacing the lactic acid with fumaric acid gives sodium stearoyl fumarate, a compound with same uses as the other two.

Stearoyl-2-lactylates are found in the majority of manufactured breads, buns, wraps and tortillas, and many similar bread-based products.
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And subsequently related:
Although it can be fermented from lactose (milk sugar), most commercially used lactic acid is derived by using bacteria such as Bacillus acidilacti, Lactobacillus delbueckii or Lactobacillus bulgaricus to ferment carbohydrates from nondairy sources such as cornstarch, potatoes and molasses. Thus, although it is commonly known as "milk acid", products claiming to be vegan do sometimes feature lactic acid as an ingredient.
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Which is good news, but still means one should ask to be sure. Which I will related some bread I like (so I hope it's vegan).

The especially iffy part is the Stearate:
Stearic acid is prepared by treating animal fat with water at a high pressure and temperature, leading to the hydrolysis of triglycerides. It can also be obtained from the hydrogenation of some unsaturated vegetable oils. Common stearic acid is actually a mix of stearic acid and palmitic acid, although purified stearic acid is available separately.
Source