I personally don't love M&D toys. We do have the tool box and some lacing cards but other than that I don't plan on buying any more. They're just not nearly as nice as the European designed wooden toys. I googled to try to find the blocks you referred to but I couldn't tell if they were really dyed. I've seen some of the baby toys they came out with that are dyed and they look much better than the painted ones but again, not nearly as cute as Haba, Plan Toys, Speil & Holz, etc.
You know, with all the recent recalls I bet M&D is working non-stop to test everything and make sure their toys don't have lead paint. I bet they would be fine. Or if you prefer you may tell your sister you prefer the "naked" M&D blocks just to be safe. They're not painted at all.
Oh, and I wouldn't trust a home lead testing kit. Those things are incredibly unreliable. Your local health dept. or doctor's officde might have a good reliable one.
Awesome SAHM to 5-yr-old son,3-yr-old girl and a baby girl. Blog about my home http://azaleastudio.blogspot.com