linear ssDNA migartion in agarose

[jqpublic at home.net]

Hello,

    I have a 125 bp PCR product that has one primer 5' phosphorylated. I
used Lambda exonuclease to digest the phosphorylated strand. Wierd thing
is, when I run the digestion products in a 1.5 - 2.0% agarose gel, the
products appear to run at about 200-300 bp, while the original ds
product is correctly running at 125 bp. Is this common for small, linear
ss DNA?  The higher the % agarose, the 'slower' it appears to run.

Thanks for any help,

c-d