New one for me.. Any suggestions appreciated.. I HWE this Carpet two days ago. Light yellow tint in this area. Appeared to went away soon as you ran the wand across it. Comes right back when it's dry. No history of ever having animals in this house ever. Off white carpet. I use the pro 10K. Rinse with Rob's alkaline rinse.. today I came back and I missed it that area with the. Rob's USOR, as it says to post spray and within 8 hours any yellowing will go away. Well it did not. So should I hot water extract this area again low pressure or is this permanent? Have no idea what it's from.