It took me awhile to finally search through a WW catalog to find out what I had ... but I did it. I believe they are Scott B5-B8, the Mozart issue semipostals from Czechoslovakia (Bohemia & Moravia) dating back to 1941:

Now for my question. Take a look at the higher valued (blue stamp). The perforations, especially in the center, look somewhat skewed. Is that normal for this issue or is it some sort of oddity?
Any comments would be appreciated. Thanks.