Speaking from experience, if the slide isn't square in the trailer wall, the seals could make noise as they get pinched when it's moving. I had to lower the front corner and adjust the slide rearward. It's much quieter now and the seals are even all the way around. If it all measures even, try lubing the seals.
2018 Jay Feather 25bh: reinforced bumper receiver hitch, TV swivel mount, bunk bed steps and grab handle, 4" memory foam topper, spare tire under bunk bed
2012 Yukon XL: Blackbear tuned, air raid intake, 3.73 gears, huge trans and engine oil coolers, equalizer hitch, rear air bags