Color variations in modern stamps are relatively common. Here’s a “teardrop”/”extra flag” error in one of the recent Indian stamps.
India Post issued a set of 2 stamps on February 17, 2018 in the denominations of Rs 5 and Rs 25 as India Iran Joint Issue. In Rs 5 stamp an extra flag in red is found on the smaller boat in the background. This variety occurs once in the sheet – Row 5 Column 4. Initially it was noticed on all sheets of this stamp. However later it was found that the sheets having color margin on top do not have this variety. Total of 501,000 stamps have been issued. I am guess there might be 2000-3000 stamps with this error out there based on the initial print run.