i found that every stair, when placed i any direction other than east,rightside up has a messed up texture.
MC-67475
Stair texture glitch
Resolved
Duplicate
1
Thomas D Pelletier
(Unassigned)
Unconfirmed
Minecraft 14w33a
Retrieved
Will be fixed for future version MC-66970 also please search or look at other bugs to see if they are or similar to your problem most likely you aren't the first one to find it.