Cat caught a squirrel today, fleas on my bed?

Yes, if there were three they'll be thousands more, you're doing the right thing by cleaning the sheets, pillows, etc. I would invest in a flea bomb, you can get them at wal-mart they cost around 8 dollars, lock the cat out and any other animals you may have out of the room and let the bomb off. that should kill them for sure, if not call the orkin man, or local pest control. They are very small, black, and jump quickly... no bigger than a poppy seed, then that is a flea..