This is just a speculative guess, but Saint Seraphim was known to greet everyone with the Paschal greeting "Christ is Risen!". It could be his way of also showing that he is in the Paschal dress that is afforded to some monastics during the Paschal season, yet was his everyday attire.
In IC XC,
Everyone baptized into Christ should pass progressively through all the stages of Christ's own life, for in baptism he receives the power so to progress, and through the commandments he can discover and learn how to accomplish such progression. - Saint Gregory of Sinai