According to this page:
https://en.wiktionary.org/wiki/%D0%B...BD%D1%8B%D0%B9
красен is a short for of красный.

According to Google красен can mean:
1) is red
2) red in the face
3) flushed
4) one good turn deserves another
Is there some idiomatic situation where красен implies some kind of tit for tat or favor for favor exchange?