Mystery Monday - First Cousins?

My great-great-grandparents Mary Ann Matson and Timothy Creeden were married in December 1868 in Clinton County, Ohio.

On the marriage license, part of it states "not nearer in kin than second cousins". The second is crossed out and first is written above it.

I am puzzling over how Timothy and Mary could be first cousins. Timothy was born in Ireland in 1846 according to all of the records I have on him and statements from my great-grandfather about Timothy's origins. If they are first cousins in the strictest sense, they must share at least one grandparent.

Mary's parents were Asa Matson (1810-1864) and Dolly Clevenger (born about 1808). Asa was born in Virginia and Dolly was born in Ohio. I do not know who Timothy's parents were.

Asa's parents were said to be John Matson (born 1758 in VA, died 1842 in Clinton County, OH) and Nancy Ann Clevenger (born 1752 in VA, died 1834 in Clinton County, OH). They were married in 1775 in Virginia. Their graves in Ohio have their age at time of death which seems to confirm their years of birth.

Dolly's parents were Aden/Adon Clevenger (born 1778 in VA, died 1853 in Clinton County, OH) and Sarah Beadles (1781 in VA, died in Clinton County, OH). They were married in 1801 in VA. Aden married Elizabeth Crouse in 1816.

In order for Timothy and Mary to be first cousins, either a sibling of either Asa or Dolly would have to be one of Timothy's parents or perhaps one of Timothy's grandmothers married into the families after Timothy's parents were born. There are several mysteries here:

• All of the siblings were born in VA and OH, so if one of them is Timothy's mother, how could he be born in Ireland?
• I have found marriages listed for all of the siblings and there is not a Creeden in any of them with any spelling (Creedon, Creedan, Credon, Credan, etc.). Could a second marriage be involved? If Timothy was born in Ireland and his mother later remarried into the Matson or Clevenger families, would that still count as a first cousin relationship for Timothy and Mary?
• Asa's mother Nancy Clevenger Matson would have been about 58 when she gave birth to Asa. That seems pretty unlikely, so are the dates or the relationship wrong? If John and Nancy are Asa's grandparents, that would leave a place where one of Timothy's grandmothers could have married into these families. This might be the most likely possibility.
• Could the first cousin relationship be once removed and be tied to one of Asa's or Dolly's grandparents? I do not know the names or origins of John Matson's parents or Sarah Beadles' mother. That still doesn't work for the Creeden name to be passed to Timothy unless there was a second marriage involved.

Obviously, more proof of all these relationships is needed. Creeden is not that common, but there seem to be a lot of them in Clinton County, Ohio during that time period. I have yet to be able to relate any of them to my Timothy, so I would love to hear from anyone researching these families!