Regina, Saskatchewan; Canada
Did you know that riddle in the singular ought to have an -s?
"\Rid"dle\, n. [For riddels, s being misunderstood as the plural ending; OE. ridels, redels. AS. r?dels; akin to D. raadsel, G. r["a]thsel; fr. AS. r?dan to counsel or advise, also, to guess. [root]116. Cf. Read.] " Dictionary.com
It's just like the word nadder that man mistook as "adder" after "an".
"Adder...illustrates a process known as false splitting, or juncture loss: the word came from Old English naedre and kept its n into the Middle English period, but later during that stage of the language people started analyzing the phrase a naddre as an addre - the false splitting that has given us adder." - Dictionary.com