I just ran an uneducated eye over the ingredients of the uncrustable in my freezer and I did not see any of the obvious hidden dairy ingredients. Of course, I could be wrong since I don't know all of them.
I appears you are correct. I was remembering a previous poster who didn't like them because her allergic kids couldn't eat them. However, I notice that they have corn syrup, so, I suppose her kids may have been allergic to corn rather than dairy.
For the OP, here's an ingredient list from the smuckers website:
BREAD: ENRICHED UNBLEACHED FLOUR (WHEAT FLOUR, MALTED BARLEY FLOUR, NIACIN, REDUCED IRON, THIAMIN MONONITRATE, RIBOFLAVIN, FOLIC ACID), WATER, HIGH FRUCTOSE CORN SYRUP, YEAST, PARTIALLY HYDROGENATED SOYBEAN OIL AND/OR SOYBEAN OIL, CONTAINS 2% OR LESS OF: WHEAT GLUTEN, SALT, DOUGH CONDITIONERS (MAY CONTAIN ONE OR MORE OF: DIACETYL TARTARIC ESTERS OF MONO AND DIGLYCERIDES (DATEM), MONO AND DIGLYCERIDES, ETHOXYLATED MONO AND DIGLYCERIDES, SODIUM STEAROYL LACTYLATE, CALCIUM PEROXIDE, ASCORBIC ACID, AZODICARBONAMIDE, L-CYSTEINE), YEAST NUTRIENTS (MAY CONTAIN ONE OR MORE OF: MONOCALCIUM PHOSPHATE, CALCIUM SULFATE, AMMONIUM SULFATE), CALCIUM PROPIONATE (MAINTAIN FRESHNESS), CORNSTARCH, ENZYMES (WITH WHEAT). PEANUT BUTTER: SELECT ROASTED PEANUTS, DEXTROSE, VEGETABLE MONOGLYCERIDES (FROM PALM OIL), SALT. STRAWBERRY JAM: STRAWBERRIES, HIGH FRUCTOSE CORN SYRUP, CORN SYRUP, SUGAR, PECTIN, CITRIC ACID, POTASSIUM SORBATE ADDED AS A PRESERVATIVE.