Its been my experinace that catfish spawn after bass by a month or so. I have caught catfish in early April when there was a skim of ice on part of the water and they did have small undeveloped egg sacks. If you draw a line from St. Louis to Kansas City, generally that spawn should take place the first couple weeks of June. Futher south its a little earlier, further north it a little later. Each peice of water is a little different, and rivers are a little different than lakes. Flatheads will spawn clear up into July when the water temparaure hits the 80 degree mark, which also seems to be a peak time for water skiers. I don't know about a spawning run so much, but doesn't mean they wouldn't. There are spawing locations that are better than others for each type of fish. Find a prime spot and it wold be very possible to catch several catfish in one area. Could be you lucked on to just such a place. Only way to find out is to go back and try it again, and by all means do so.......every chance you get. Your right, they are a blast to catch and they are great fried in bacon grease and sprinkled with lemon pepper.