I should point out that the Lectionary indicates that if the distribution of ashes occurs outside of Mass, the Liturgy of the Word, with the readings for Ash Wednesday, should be part of the service. This appears to not have happened in your case.
The Lectionary has:
“ASH WEDNESDAY
When the blessing and distribution of ashes is done apart from Mass these readings may be used for a liturgy of the word before the blessing of ashes.”
(Lectionary Volume 1 Study Edition, Collins Liturgical Australia, 1983, ISBN 0 00 599764-X, page 187).
It uses the word “may” which suggests flexibility in the choice of readings.
The Book of Blessings ceremony, approved for the USA, seems to say just one reading. It has:
“1665 A reader, another person present, or the minister reads a text of sacred Scripture.
Brothers and sisters, listen to the words of the prophet Joel:
2:12-18 …”
After the text of the reading it has:
“1666 Or:
2 Corinthians 5:20-6:2 - *Be reconciled to God, now is the acceptable time.
*Matthew 6:1-6,16-18 -
Your Father, who sees all that is done in secret, will reward you.
1667 As circumstances suggest, the following responsorial psalm may be sung, or some other suitable song.
R. Be merciful, O Lord, for we have sinned.
Psalm 51”
After the text of the psalm it has:
“1668 As circumstances suggest, the minister may give those present a brief explanation of the biblical text …”.
(Book of Blessings, Liturgical Press, Minnesota, 1989, ISBN 0-8146-1875-8, pages 623-624).
So someone following this book, not looking at the Lectionary, would believe they should only do one reading, which should be before the psalm.
It is interesting note that the Lectionary does not envisage a separation of the blessing of ashes from the distribution of them. It has “When the blessing and distribution of ashes is done apart from Mass these readings may be used for a liturgy of the word before the blessing of ashes.” This highlights how unusual the Book of Blessings ceremony approved for the USA is.