Can be painful never the less .I had them behind both knees and one burst .. I had a leg like an elephant and it was very,very painful when walking .Then they come at you with a needle and draw the fluid off .
Keep an eye on it mintymow especially if you are on your feet a lot ..I developed them in both knees in my forties and fifteen years on am racked with arthritis .It's one of the first signs that you could get dodgy knees in later life .I seem to remember at the time the doctor gave me some gel to rub in called Traxam which helped and of course put your legs up as much as you can .Alternate heat and cold packs can help too.It will go down in time .
But apparently it's no big deal .