Power Steering Mistery?

2003 Odyssey. Changed oil and checked fluids. Opened red power steering cap to check level. Put cap back on. Finished oil change. Took car for test drive and power steering starts getting sluggish and making whining noise. Opened the hood and found power steering fluid all over the passenger side of the engine. Source of leak came from cap. Power steering fluid level was good before I checked it, and I have never had a problem with power steering before. Things I have done to diagnose the problem were bleeding the lines by removing the cap and turning to max both ways. The fluid did appear to be very foamy. This got a little better, but fluid continued to leak out and it continues to whine. Fluid levels are at upper line after I topped it off after bleed. Does anyone have any clue as to what damage I could have caused by simply removing the cap? Please help.