Just as Midge says - outgassing and once you get more coats on with a sand in between and it will be great. I had exactly the same problem when coating a boat with West System (and other epoxies too).Looked like a non-skid hull! West reccommend that you coat as the temperature during the day starts to drop rather than rise to minimise the outgassing. I have also had an inapropriate outgassing:o after coating a deck with a decking oil no doubt for similar reasons and with a similar solution.
cheers
Salty